Hello I have a 2004 Flex Fuel Tahoe with a 5.3
a couple weeks ago I went to start it after a cold night and it ran for a split second and died. Then it would just crank. Even cycling the key multiple times to let the fuel pump pressure up. It would only start when I pressed the gas pedal down. It would run rough for a second or 2 and puffed a bit of smoke. Then it would run completely fine. It did it again yesterday and today. Only after it sits overnight. Fuel pump turns on and sounds fine. I don’t think I am loosing fuel pressure

 

The only way to know for sure is to check the fuel pressure. Just because the fuel pump is running, doesn't mean it is getting enough pressure.

 

My 93 does this on start up, especially when cold. My impression is at start up it it too rich (like a carb with too much choke). For my throttle body I feel pedal allows more air clearing the problem - but I have not figured out a fix