I need some advice. I have a 2000 Suburban 2500 with a 6.0. The problem I'm having is when I start it after running it for awhile maybe like a hour after running it It will start fine but idle at like 300 rpm for a few seconds while hesitating and then I smell gas for a few seconds. It never dose it when I first start for the day and if I shut it off for only like 15 minutes then restart it's fine. also I noticed when it dose it I lack alot of power for a minute or two of driving. I have changed the plugs/wires and even cleaned the IAC valve but its till doing it once in awhile. Any ideas would be great thank you.

 

I'd look at the fuel pressure regulator

 

Had some what the same problem. I changed the coolant temperature sensor everything went away.