I have a 94 GC with v8.
When driving it acts like I am short on fuel. I noticed it the other night while heading home. I could not go faster than 60 mph. When I mash the foot feet to the floor, I begin to loose power and slow down. (decelerate) I replaced the fuel filter, that didn't help. It also didn't seem plugged.
The fuel on the rail reads about 39 psi at idle. When I shut the engine off the pressure drops down just a little. When we hit the drain button on the pressure gauge you can see air bubble in the fuel. We let it idle and bled off the fuel into a jug. eventually we got rid of all the bubbles. We depressed the foot feet to the floor and were able to go up to about 4400 rpm but it quickly dropped off. We looked that the fuel again, and had air bubble back in the fuel.
What is causing this? Pressure regulator or fuel pump?

 

Sounds like a faulty foot feet to me.

Have you tried to look for one in the parts store?

In my local store it's beside the blinker fluid.

 

I concur with this^^