I have a 1994 camero RS that had same problem. It was the idle control valve. It cost 97.00 dollars to replace it. You can usally clean it/ It is part of regular maintence of the car. If you look at the intake where the rubber meets the metal part right to the left there are two electronic valves connected. The upper one you want to remove and spray off with carb cleaner. Note:
you will need to buy a special tip for your screw driver for the odd bolt. This will help alot if it does not replace the valve. I followed these steps and it fixed the problem.