00 Chevy suburban has a slow start and then dies out.?

[chino 323]

i have a Chevy suburban and in a cold start it cranks up slow to turn on then it dies out!! got to keep the gas pedal in for a few seconds for it to stay on. then when i finally get to turn and stay on i change the gear and it turns off!! I change the starter,battery and the alternator. I filled the tank with supreme gas and fuel injector cleaner

plz help thanx!!!