I have an 07 chevy with a 6.0 in it. On Cold starts it will long crank start and stumble and stall. It may do this 3 or 4 times until it coughs a few times and shakes and comes out of it. It was at the dealer for a couple days. Had no codes. Fuel pressure was in spec and held over night. Mass air sensor was swapped with a known good. Throttle body was functioning correctly. Plugs were changed, 2 were heavily carboned with only 20k on them. I've put a new throttle body on it since. Ran injector cleaner in it. Dealer updated the computer. Not sure what else to do at this point
Probably leaky or clogged injector. Fuel trim probably rich. Check data with scan tool to confirm when it starts. Check spark plug if it smells like gas after it sits overnight.
Run Bernie's injector cleaner or AMSOIL's PI. May have to add a bottle at several fuel ups.
