Got it. Fuel pressure is regulated by engine vacuum, and those numbers with the engine running are consistent with what to expect depending on pedal position.

What’s it doing at key on, engine off?

 

Sitting at 55 psi.

 

If it’s holding at 55 for at least 5 minutes, fuel pressure isn’t the problem.

Have you checked the TPS for an open? An analog meter works best but a digital will also work. Set meter to ohms and probe the TPS on pins A (gray wire) and C (dark blue), then slowly open the throttle by hand. The resistance should steadily increase (or decrease - I can’t recall which at the moment) as you actuate the throttle. If at any point the meter reads an open circuit, the TPS needs replacement.

 

I don't know if anyone else noticed in his video or not, but the engine seemed to move around a lot. Was that something like a misfire or a surge? Also, if you rev up the engine slowly does it not stumble?

 

I don't know on the misfire/surge. There is no cel for misfire. It doesn't matter if I slowly rev, or floor it. It will still stumble.

 

@CJG_GTX Interesting... I am no expert, but I figured I would bring it up, so that people who know more than me could use it possibly.

 

I didn't initially try to watch the video because I don't have a facebook account and I didn't think it would let me view it - just tried and was able to watch.

The movement of the engine does indicate worn mounts - there's 1 on either side under the exhaust manifolds and the mount at the rear of the transmission - torn bushings are definite need for replacement - if you can use a pry bar and get more than about 1/4" movement out of them, they should be replaced.

The stumble itself does indicate possible air or fuel starvation, but it also indicates possible timing issues. When you replaced the cam sensor, did you pull the distributor? If so, verify the timing is correct - for some reason these distributors are tricky to install. Multiple times at work I've been certain it's installed correctly, yet it's still somehow off by 1 tooth. If the flat on the distributor cap is not parallel to the intake manifold, the distributor is off by a tooth - minor adjustment can be achieved, but it only has an acceptable adjustment range of 4* total (-2 to +2 @ +/- 1,000 RPM - must be read using a scan tool) so the distributor cap should not be offset by much when compared to the manifold.

Try unplugging the EGR valve to see if that eliminates or reduces the severity of the stumble.

It looks like you've got a 5.7L - is that right?

 

I replaced the distributor cap, Rotor and cam sensor. It was while I was trying to fix the issue I'm having. I will have to check the cap.

Yes, It is the 5.7l.