That means that it is time for a tune-up for sure. My car did that this past week, and it was due for a tune-up and an overdue one at that too. Also have your Chevrolet/GM dealership do a Check Engine light test to determine that it is that, and if it is that, then see how much it could be to have that done. Also if it gets too pricey, check around like to Midas or to NTB to see how much they would be charging for that. Also if you take it to a gas station, be careful...they could be pricey there too.