Ok changed fuel pump because truck would start right up then dies after couple seconds. I drove it with new pump for 3 days and got stranded. Truck doing same thing as old pump. The three days it ran it ran with new pump it ran perfect. Now starts right up but starts running rough after few seconds then dies. I pulled bed back off and made sure wiring is good no black spots. Is there a relay somewhere besides the 4 prong one in fues box under hood?' Does fuel line have restriction maybe?. I have new 2nd new pump coming tomorrow. I pulled air filter and truck died immediately. When I turn key on pump starts and runs a few seconds then shuts off. I immediately turn key off and turn back on pump will not start. Wait 5 minutes and pump starts every time. I can't believe no one can figure this out. Does Evap solenoid have anything to do with it? I'm grasping at straws here. Please read thoroughly and brain storm this because it seems I have a unique problem or problems.
Check the bottom of the fuel tank for sediment. Age and mileage could have accumulated a lot of it at the bottom of the tank. If you did not, check and change the fuel filter. Rule of thumb - replace the fuel filter any time you replace a fuel pump. Also, check the wiring for any chaffing on the fuel pump when you remove it. While your problem is kind of unique, I have seen many GM truck fuel tank baffle loosen over time, occasionally rubbing against the fuel pump can intermittently short it out and/or block the fuel pump pick up. To have this diagnosed, consider having a certified expert from YourMechanic inspect the stalling issue to have this corrected.