1989 Ford F-150 question

I have a 1989 ford f150 lariat xlt that keeps dying on me. It will idle great for hours without overheating or stalling but when I am driving all of a sudden it will lose power, the gas pedal will go soft and it will eventually die. After it dies I cant get it to fire back up unless it sits for about a half hour then it will run fine for a while and eventually do the same thing I have had the coil replaced recently by a mechanic that swore that was the issue then another mechanic Said it was probably the fuel pump, so they tested it and it is working fine they say I have had 3 different shops with different theories and none of their theories have fixed the problem I dont want to pour anymore money into things that aren't fixing the problem, please help