engine starts but wont run on

I'm having the same issue, my 2000 Yukon 4x4 slt, 5.3 had been running just fine, except for the change oil light, started then stalled, stared it again ran to store, then went to start back up wouldn't stay running unless I kept my foot on the gas pedal, kept a foot on gas and brake pedal, got home sat a week starts, idles no problem drove it no problem ? Didn't stall at all confusing. I had replace the fuel pressure regulator that's on the fuel rail some months ago was acting the same way, a bad or failing ECU will cause the same problem. I had a front axle 4x4 actuator go out wouldn't start replace it ran fine ? My Yukon has 300 thousand miles on it, maybe the Mas air flow sensor or the air control sensor or fuel pump. It's running fine again.