My wife was driving the Envoy today. She was parked overnight and in the morning went to start up the truck. It sounded like a WWII tank engine running very rough almost like it was firing on only three cylinders. Turned off the truck for a few seconds and tried to start it but it only cranked. Finally after four tries it started but was very sluggish at first Almost like it was flooded. Very strange. I have experienced the same issue before a couple times. Seems to happen if I turn the ignition off and then on quick.