89 3/4 ton Silverado engine dies

I have a problem with my motor dying....its a 5.7 TBI. It runs for about 3 minutes then dies.......then it won't start for 10 minutes.......then runs for 3...so on. I replaced the fuel filter....that didn't help........I replaced the map sensor and that didnt help. It seems to have good fuel pressure up to the injectors.......and fire at the injector wires.........................Any Help??............Thanks nailgunner