I had one after driving up a steep hill in 1st gear through lots of dirt with the gas to the floor.
It was my fault and the light came on but to make a long story short,
call onStar. I was impressed they new it had bad idleing even without me saying anything. They can give you some good information but tell them not to clear the on board computer.
If OnStar sees it and it still is happening take it in.
My issue fixed itself.
