Fuel Injection problems of the 2000 Saturn LS

I drive a 2000 Saturn Ls and for the past 6 months my service light comes on periodically and the ac/hear/defrost will not work. There has been a new sensor system placed in the car and I have flushed and used the fuel injection system and changed from using regular to mid grade gasoline and I am still having the same problem. The dealership (was Saturn is now road show auto) has tried everything to correct the problem but the problem still remains.

While driving 80 mph vehicle stalled. Consumer was unable to restart vehicle. Consumer had vehicle towed to the dealer for inspection, and mechanic determined that the air sensor needed to be replaced. Please fill in additional information.