need help please!

Ok, I have a 90 FSB with a 302 and an AOD. I have been having problems when I have been driving after a while it will start loosing power like it is running out of gas or has low fuel pressure. So I did some testing and sure enough not enough pressure. So in went a new fuel fitter and fuel pressure regulator. Same results so in goes a new fuel pump. Seems to be better, pressure is where it should be. yet after driving for a while (some times I get 50 miles, some times I get 3 miles) it does the same thing. Usually I can pull over, turn the truck off, wait like 30 seconds and start it again and I will get another 3 or 4 miles or so and I will do it again. Just to add in it has new plugs, wires, cap, rotor, coil, and the trimming was just checked and is right. Please chime in with some ideas. It is driving me nuts!!