Just started running rough, coughing, almost stalls.
So far I pulled the plugs and they are clean. I cleaned a small amount of corrosion/buildup off the distributor cap contacts. Also pulled the cam and crank sensors to test them. They both tested good. So after those get installed I'm down to knock sensor or fuel pressure regulator leaking.
When I start it cold it will idle great for the first couple minutes and then right when it should start idling down it starts sounding like it has a huge cam or else 20-30 degrees of timing are pulled. I doubt it is the fuel regulator because all plugs are dry and white/golden. I've had plugs dripping wet that still fire.

It feels and sounds ignition related so I'm open to anything I might have missed.

 

Have you checked and cleaned the EGR valve?

 

Yes, that was day 1. It's still really clean from the last time I had a problem and it was the EGR. It could have a weak spring though. Not sure how I could tell though.
It has a code but I cannot check since it's a 95 and I refuse to take my vehicles to a shop.

 

Removing the crank & cam sensors just forced you into taking it to a shop with a capable scan tool Before you continue with diagnosis, the crankshaft position sensor relearn MUST be performed. The PCM uses crankshaft position sensor data for ignition timing and injector timing. It tells the PCM exactly where the crankshaft is in its rotation. Pretty much how it got its name of crankshaft position sensor The sensor is "focused" in a very small area, and each sensor is unique. The crankshaft position sensor relearn procedure "teaches" the PCM precisely where the sensor is focused on the tone ring. The relearn data is burned to a file in the PCM, and it remains there until the next relearn. The procedure is initiated with a capable scan tool, (the El cheapo's can't do it). Once initiated, it takes roughly 1 to 2 seconds to complete. If the sensor and or timing cover is moved, removed, replaced, or disturbed in any way, the focus area changes. When the focus area changes, the sensor does not provide accurate data to the PCM. The engine will still start and run using the original relearn data, but the PCM will be using the old relearn data, which is now incorrect, which causes ignition timing & injector timing to be incorrect.

After the relearn, camshaft retard MUST be checked & adjusted using a capable scan tool as well. Have the shop give you the DTC's too.

When those are done, we can help you with diagnosis. Without doing both of them, the engine will not run correctly, guaranteed.

 

Camshaft retard checked? Gm must have thought they were reinventing the wheel with this stuff. Either you are making it sound more complicated than it is, or it really is more complicated than it needs to be. What is the point of a distributor if they used all the sensors required to not need one?

 

Yes, it must be at least checked, and adjusted if necessary, if the distributor hold down bolt is loosened. Rotating the distributor aligns the camshaft position sensor with the camshaft. The PCM uses the data, along with the data from the crankshaft position sensor, to detect and accurately identify cylinder misfire. The I.D. of the distributor is smaller than the O.D. of the hole in the intake manifold. This allows the distributor to be rotated slightly. The data stream can only be accessed on a capable, (high end) scan tool. Adjusting camshaft retard is part of the job when installing a distributor on this engine. Just like adjusting ignition timing is on an older style distributor.

 

Got it all back together and it fires up and idles as it did before. I even had the knock sensor disconnected and it did it.
Tested fuel pressure and it pumps to 60 and drops like a rock. I guess it's either the 1 year old regulator or the 1 month old fuel pump. Running pressure is at 60 and stays there.
I noticed a knock or tapping sound that it did not have before. I guess I'll go through the fuel system again.
I have not cycled power to the PCM, who knows that just might fix it.

 

Day 6 troubleshooting:
So I'm going to start off by:
1. Checking TPS voltage.
2. I am interested in seeing what the MAP sensor is seeing though.

Maybe I start pulling sensors to get it into limp mode and see what makes it run the best.
3. Finish up with checking the spider assembly, check for leaks. Could the pressure regulator be leaking through even though I still have pressure?

 

Better go after the fuel delivery problem first, a drop to zero is a serious problem. Check pressure and leakdown at the fuel filter outlet first. All pressure and flow must end at the tester, with no fuel allowed to the engine. Post your results.

 

Good and gooder news. I found a scanner that will connect and read the codes... good news. I found no codes but the ones I caused.
Gooder news is that I was correct about the fuel pressure regulator. I pulled the plenum and cycled the key. No leaks. I did notice air bubbles in the return line though. So I pulled the regulator and found a piece of o - ring. The small one in the center was damaged probably during install. Good thing it waited until late December for the problem to show up.
I'll get it together when I find an o - ring and see what happens.