Ok i recently aquired a 1988 f250 4x4 custom. 4.9l6 and a 5 speed. Ive been having troubles with a rough choppy idle, alot of hard shaking under acceleration, and once warm it will die. It usually wont re start under any conditions untill its cooled off. However the more i use it the longer it takes to restart. It has done this once before and it was a bad fuel tank selector valve. Seeing how its missing the front tank i just removed the valve and have lies straight to the high pressure pump from the rear tank. This time it seems like a weak ignition. What is new: rear fuel tank, high and low pressure pumps, fuel pressure regulator, coolant temp sensor, plugs, wires, rotor, cap, ICM, coil, and map sensor. I have cleaned the IAC and the intake manifold has been removed, cleaned, and re -gasketed. Upon trying the old trick of pulling codes through a self test the first time it flashed several codes ( most of which emission control) after fixing all of the codes i cleared the ecu ran the truck through the ford driving cycle (dying several times) and re tried the codes. The light will flash only one time and go out. This truck is vital to the farm and any help will be greatly appreciated.

 

You're doing the right thing by trying to get the codes first. However, getting the codes without a code reader can be tricky. Try to get two or three consistent readings KOEO so you know which codes you are getting. Once you get a pass on KOEO then proceed to KOER codes.
With all the fuel related work you've done recently I would look at the fuel pressure in the system too. I don't know where to check fuel pressure on your system as mine only has pumps in the tanks (I believe.) There's a schrader valve on the fuel rail at the back of the engine where the fuel pressure gauge is attached. Others here will be able to direct you as to where to test your system for pressure.
Sometimes, when a vehicle quits when warm and won't start again until it cools off, it is an electrical issue. My brother had that issue with one of his cars many years ago. It turned out to be his coil. Once it was warm it stopped working and he couldn't get the car going again until it cooled off. Having said that, check all of the wiring that was moved, touched, changed while doing the work mentioned. Especially the grounds!
My guess is you have several things going on at the same time. A systematic approach will get you going in the shortest and cheapest manner possible.

Good luck

 

Did you check for spark, thats what i'm thinking either the module or the pickup in the distributor, check and make sure you have a good spark and when it dies test it again, the ole screwdriver in the coil wire will work should close a half inch gap.