Here is some info.

95 s10 Blazer 4.3v6 4wd On the floor. It has the CPI with the Black plenum cover with the orange Vortec label above the plenum. The distributor is vertical. - According to previous owner it has a new fuel pump, fuel filter, Rotor, cap and button. & Alternator. - (I know this doesn't mean none of these is the problem)

I traded a 94 Camry for this vehicle, due to it being in pretty good shape, except for the fact it was running like crap. I pulled the plenum and did KOEO to prime the fuel pump. I seen that there was a good leak on the Fuel Inlet hose on the nut kit due to one of the spider wires rubbing on it. I replaced the nut kit only (Didn't replace spider because I don't have the money to do that right now). New intake plenum gasket, cleaned the lower intake plenum and upper intake plenum, cleaned EGR passages (they had approx 1/8" of carbon all around the EGR passages) New EGR gasket also. cleaned throttle body and throttle plate also.

Was running way better, but no perfect. Idle is pretty smooth. But when under light/medium acceleration I get a random hesitation and misfire and then it goes to running smooth for a while. I get upto highway speeds 55-60mph and a few minutes later it'll stumble and i'll hear a couple of quiet pops out the tailpipe. - I asked a local backyard mechanic to drive it up and down the road a couple of times and he told me it seemed to him that the Distributor Ignition Module was bad. So, I went to Autozone and got an Ignition Module and put it in. Seemed like most of the stumbling had gone away, but it still has a little sputter at highway speeds. Also the RPM tach will jump from 1800RPM to 2000RPM when it does this and back to 1800RPM and so forth.

I just noticed that a retainer clip had come out of the distributor somewhere. - (I believe it's called a retainer clip) It looks like the little piece of metal that goes in the flat side of the rotor so the rotor has no freeplay on the shaft. I took the cap back off and was about to put the clip back in the rotor... But it already has one! I dont know where this clip came from, but I noticed that the bracket that the cap bolts down to has a real small amout of freeplay in there. (I'm not sure if it's supposed to have that) When I bolt the cap back down the freeplay in the bracket (obviously) transfers that freeplay in there to the cap. I'm not sure if it's causing my problem i.e throwing it off time whilst going down the road.

My second problem is cranking the vehicle. I turn the key, wait for fuel pump to cut off, turn motor over for approx 1/2 a second let go, turn motor over for another 1/2 second and vroom! It'll crank right up. - If you crank it like you're supposed to in any other vehicle and just turn the key it will turn over and over, but never start! - I've not done a leak down test yet, I have extremely basic tools - Socket set and wrenches. Lost my voltmeter and don't have a fuel pressure gauge. - I believe I may have a voltage drop, but havent had a volt meter to test, however I know I need to do a fuel pressure leakdown test first...

I'd really like to get this problem fixed and will give as much info as i need to you if you need any extra. - Excuse me if I've done something simple wrong but I've never had to work on distributors.

I hope I've provided enough information for you to be able to help. Thanks for your time.

 

Gotta start somewhere, so we might as well start with the simple stuff

Fuel pressure and leakdown must be within specs, it is critical on this engine. It's also a problematic system. Most auto parts stores rent/loan fuel pressure testers for free. They sell them for ~$40, and every Blazer owner should have one in their tool box It is very easy to check, takes about 15 minutes, and will tell us if the fuel delivery system is working properly. Let us know when you have one available, and we can walk you through the tests.

 

I'll get hold of a Fuel Pressure Gauge tomorrow and post results. Thanks