Update and a question, apologies in advance for the long post:

This past weekend, I was planning on taking off the distributor cap to check its condition and see how much play was in the shaft. Turns out all my screwdrivers were too long to fit in the space to take it off. So I was going to test the coil, but I wasn't sure how to do that properly since the illustration in the Haynes manual for the coil isn't the same as what is in my truck. Also couldn't find how to do it on Alldata either. When you click on testing and inspection under ignition coil, it tells you to look under EI system diagnosis under computers and control systems, but ignition coil isn't part of that list. So anyway, I didn't test the coil, so when I was putting the wire back on, it wouldn't seat properly. I looked in the terminal socket, and there was a piece of metal in there. I looked at the wire, and didn't see any part that was missing a piece of metal. So I hooked everything back up. I also changed the fuel filter that day. After this I took the truck for a ride to get a stubby philips head for the distributor cap. The truck ran great! I drove it about 20 miles, no problems. So I cleared the P0300 code and hoped for the best. I figured either the errant piece of metal or the filter change might have fixed it. The next day, drove it 50 miles, no problems excpet for a slight hiccup with TCC lockup, but that was only once.

Fast forward to Tuesday, I drove it to work, ran like crap again, maybe even worse. Same symptoms, rough acceleration, no TCC lockup, seems to "lurch" at highway speeds from the misfire. SES light on again, flashing even more than last time. Same code, P0300. So back to square one.

My question is about fuel pressure. I know I stated before that the pressure was good, but I have been reading some post on here that made me second guess myself. Is the pressure supposed to drop after the pump shuts off when doing a key on, engine off test? The pressure was around 63 PSI when the pump started up, but when it shut off, it dropped to around 55 PSI. It stayed at 55 for around 15 minutes or so. In the diagostic chart for testing fuel pressure, step three says that the pressure may vary after the pump shuts off, so I wasn't sure if that meant that it was supposed to drop as much as it did.

I found this link: Part 1 -GM Misfire, No Spark/No Start Tests (4.3L, 5.0L, 5.7L). while searching this site so I will see if I can use some of the info there.

 

The distributor cap hold down screws are torx, not phillips. In a pinch, an allen wrench will work. Be very careful: the ears on the distributor are plastic and can break or strip out very easily. If/when that happens, it's time for a new distributor. Look for one with an aluminum housing, much better design.

Haynes, Alldata & Chilton manuals are all just about worthless, as you just found out. If you want a shop manual, get a GM "dealer issue" shop manual for your year vehicle. Three separate books with over 3,000 pages that cover your year, make and model only. It covers everything ...period! You can usually find them on Amazon & eBay.

Your fuel pressure & leakdown results are fine. When the pump turns on, pressure should be 60psi to 66psi. Your reading of 63psi is fine. When the pump shuts off, pressure will drop slightly until the check valve in the fuel pump seats and seals the pressure. Pressure must remain above 55psi for at least 10 minutes. Your reading of 55psi is the lowest allowable, but it is within specs.

Next step is check camshaft retard, and adjust it if necessary. Being that the distributor has been out, there's a 99% chance, (maybe more ) of it being incorrect.

 

I'm am 99% sure that the screws that hold down my cap are not torx. At least the one in the front is a silver philps head screw. Possibly misplaced by the shop that did that work a few years ago?

I haven't actually figured out if the distributor is bad or not, hopefully this weekend. Since I would need that scan tool to correctly view/adjust that camshaft retard, maybe I'll just let a shop so it. Though I've been thinking of buying myself an early birthday present and getting the GM enhancement package from AutoEnginuity. I'll see what happens.

Thank you again Captain Hook.

Edit:
Today I pulled the cap finally, and was right about the philips scew, it was a sheet metal screw about an inch long. The reason it was there I have a feeling was because, like Captain Hook said, the plastic ear was broken off. Looks like at some point it was rigged up with that screw, either by the shop I had it at or by the previous owner. The cap has some white corrosion, and the rotor looks okay, I think. I wasn't sure how much play in the rotor was too much. The diagnostic chart for P1345 seems to say that there should be none at all. Got crappy video here to show the movement:

http://www.youtube.com/watch?v=Kdb-d...ature=youtu.be



Here's a photo of the underside of the cap, linked since it's large: http://imgur.com/5OAqT

So I guess I have to replace the distributor anyway, since the cap isn't held on very well. One question, I know that AC Delco is the preferred brand for the cap and rotor, but their distributors still I have the plastic housing, right? I'll have to get an aftermarket one with the aluminum housing, but will I have to spend extra money on the ACD cap and rotor? Or will the cap and rotor that comes with the distributor be good enough?

 

Bumping to see if anyone has an opinion about whether or not I should buy a separate AC Delco cap and rotor when I get that new distributor. I was going to get this one: Manufacturer Info Part number 9363 United Ignition Wire.

 

Aluminum housing distributor is the only way to go. It sounds like you don't want any problems, so, use an AC Delco cap & rotor. The "corrosion" you saw on the distributor cap terminals is crystalized silicone dielectric grease. It is supposed to be there, so put a dab of silicone dielectric grease on each terminal, inside and out, of the cap when you install it. When the engine is running, current passes through the grease and it crystalizes. Don't forget to have camshaft retard checked/adjusted after you replace the distributor. I wouldn't even save that blue cap for a spare, toss it in the trash right on top of the Haynes & Chilton manuals

 

What's your take on brass terminals instead of aluminum in distributor caps? I was reading some threads here and the consensus seemed to be that brass was better than the aluminum found in stock caps. The distributor that I'm getting has brass, but I guess it's still junk? You're right, I don't want anymore problems, so if buying a separate ACDelco cap is the way to go, I'm absolutely going to do it.

In that video I posted, was the movement in the rotor excessive? I already ordered that distributor, just hoping that I'm not jumping to conclusions here.

 

What you're seeing in the distributor shaft, (in the video) is slack between the distributor gear and the camshaft gear and that is perfectly normal. What's more important is the side to side movement which you really can't tell much just by moving it with your hand, unless it's really bad. The ignition waveform must be viewed to determine if the shaft bushings are worn excessively.

As for the distributor cap terminals: the material is not nearly as important as the construction of the cap itself. The main problem aftermarket companies have is that they haven't figured out how to properly insulate the conductors from each other inside the cap. As a result, they leak current causing crossfire, that's where the P0300 series DTC's come from. Some aftermarket caps last longer than others, but none of them last as long as an AC Delco One very well known company has an extremely high failure rate... right out of the box! Certain parts you can use aftermarket, others need to be AC Delco.... experience knows which parts they are


Edit:
Annealed copper is the best (practical) conductor of electricity. Aluminum is about 60% of copper, and brass is around 30%

Source: http://www.eddy-current.com/condres.htm

 

I like the Accel cap and rotors, NGK or Denso plugs, even Autolites. They cost less.

I don't have as much faith in AC Delco as Captain Hook.
What to use for spark plugs? - S-10 Forum

 

Today I tried to install the new distributor using the #1 method (mark rotor alignment and try to match same marks to new distributor. Of course I ended up with a P1345 code. So I'll have to use the other method tomorrow. Couple of questions. Is there a trick to actually see the timing marks on the front of the engine? I've looked from above, below, and from the wheel well and can't see a thing. Also, the new distributor doesn't have a paint mark on the shaft, or a "6" molded anywhere on the base. Any idea how I'm going to get this lined up properly?

 

With a socket and ratchet, manually turn the crankshaft ONLY in a clockwise direction until it lines up like this AND the rotor is pointing at, (or close to) the "6". If the rotor is not pointing directly at the "6", P1345 will set. Then pull the distributor out and reinstall it so the rotor points at the "6" when the distributor is fully seated against the intake manifold. Don't worry about the paint, only the original distributor will have it.