I've got a well running 2000 GMC 3500 7.4 liter 454 auto 4x4 67000 miles
Starts instant in the morning, starts good after a few minutes shut off, but drive it and shut it off for an hour up to half a day or more and it's hard to start. Long cranking seems to be helped by moving gas pedal but I don't know if that's a fuel thing or telling a sensor to take another reading. Stumbles just slightly when it starts then runs fine and dandy.
I've cleaned up the map with a couple cans of spray
What's the most likely suspect?