'91 w/5.7 77k miles has a surging problem also. I noticed my fuel regulator makes a ticking noise that seems a little loud to me. Does yours?
Here is what I've also noticed:
1. Key off at idle 40psi.
2. Running at idle fuel 30psi, vacuum 20lbs.
3. While driving fuel 38-40psi, vacuum 0lbs.
4. Fuel injectors check good. 17.2 cold and 17.9 hot

I thought the loud tick was from my cap and rotor but its the fuel regulator. I can also feel the "pulse" of the tick in the pressure gauge hose.

My surge is as I drive, mostly 2000rpm, no codes. It all started after I was playing around "gunning it" by tapping the throttle making the car jump a few times then I went about 100-110mph and as I went back down to 65 I noticed the surge. The car will still pull but it also surges as it does.

Ive replaced the cap and rotor and know I need plugs and wires but i dont think they would cause this surge.

So what do you think?

 

I am also looking at a fuel problem. One thing I noticed that you have the same fuel pressure at idle as what I do basically. I think 30psi at idle is too low?? I would have thought it should be around 36 and as you increase load it should climb up to max 44PSI.

One of the reasons I am trying to find a fault because of the low fuel pressure I think.

 

Im wondering if my knock sensor would pick this up this tick and and adjust the spark to cause my surge?

My other thought is my car always reads low temps.maybe the thermostat is cracked open causing it to not warm up which causs it to run rich which causes it to foul up the egr? Just a thought.

 

I have the same pressure / ticking problem you did
Did you ever figure out what it was?
Bad regulator?

 

This year Ive only had the car out a few times. After sitting for about 5 months during the winter months it hasnt made the surge. It still makes the tick. I dont drive it often at all but still hope to replace the regulator sometime. Good luck with yours, Ill let you know if I find anything.

I want to replace my regulator, plugs, wires, egr and regulator.