Help with a 87 F-150

I have a 1987 F-150 with a 4.9L and 5 Speed with an electrical gremlin. It currently will sart up and run fine untill it warms up. Then if I shut it off and try to restart while its warm, it does not have spark or fuel injector pulse. After cranking for about a minute or more it will slowly regain spark and restart. I am tired of throwing parts and money at it, but its hard to diagnois since it only does it when its warm. I have already installed a new motorcraft distributer, a new igntion controll module, new msd coil, remanufactured computer, all new fuel pumps, new fuel tank selector valve. Any suggestions would be greatly apprieciated.

Regulator valve, does it blow black smoke when it does start?

My Daddy had the same problem with my 86 f150 when he had it .He changed evrything you did come to find out it had a bad ground on it.It was the ground wire off the battery the little black wire it had a plug on it,it was not making a good connection it looked fine but wasn't making a good connection in the plug.We changed it out and never had another problen out of it.Just something you might check hope this helps.I hate wiring shorts I have a 94 buick regal grand sprot that was give to me that got a short I can't find for ^%&$$%*.

No smoke when it restarts. I will double check the grounds.

I checked the entire wiring hareness for loose conections or corrosion with no luck. I am thinking about trying a computer from the junkyard.

Check your ignition switch, ground at the battery ,ground from the engine to chassis, and check your starter solenoid. good luck