87 F-150 4WD, won't run when hot

I have an 87 F150 302 fule injected. It runs fine when I first start it when its cold, but after while when it warms up it hesitates when I hit the gas and most of the time it'll die. Any time I try to start it when its warm even if I shut it off, it will turn over and not fire, but when I hold the gas down it will fire once and send out a big puff of black smoke and then won't start. It will do this every time until it cools down. Then it will run like it did when it was cold. A friend suggested that I replace the idle air control valve, so I did and it didn't change anything. I'm at my wits end and need to get the succor goin'. What should I check or do next?