unsuccessful

I have some problems maintaining the club wagon with the 302 engine. When I start and drive no problems until maybe ten minutes when all of a sudden it stumbles and cuts out on me. I try to restart it and it cranks but doesn't kick over. I wait maybe two three minutes and it starts back up. sometimes i can make it home without it stalling again, other times it will stall about four times before i get home. I have replaced the IAC valve and had no problems for about two weeks and then bam, it did it again. I went ahead and replaced the egr position sensor, tp sensor, fuel pump relay, eec relay, external fuel pump, fuel filter but it continues to die on me. today was the day i replaced the tp sensor and about 3/8 mile down the road it died. I restarted it and put it into gear and died. waited a minute and started it, put it into D and let off the brake and allowed it to coast me home (bout two blocks). Parked it and revved the engine and when it revved down it stumbled, backfired slightly, and died. I can go outside right now and start it without a problem. As soon as I drive it or if it idles there for a couple minutes it dies. the internal pump (fuel) is good. the spark plugs and wires and distributor, etc., are good. anyone with any suggestions? this has me stumped