2006 Chevrolet Colorado Erratic idle after warm startup

My Colorado starts normally every morning and evening, regardless of temperature, provided it has been sitting for hours. The problem is it is difficult to start after cooling off a little. An example would be a restart after the truck has been running and then turned off for 15 or so minutes, ex: trip into a convenience store. Crank for a long time and it will eventually start, rev high but rough, then almost die and kick up again. It will do this several times before it dies. The truck will require 3 - 5 attempts before it starts and runs normally. Through all this I never touched the gas pedal or placed it in gear. When it's running it runs fine for a truck with that many miles. Haven't found any answers on the various Colorado forums I've visited. I'm sure it's getting fuel, I think it's spark/timing related, all controlled by electronics now days. Any ideas?