Got one update. 90 RS: had shifter loose? They torqued a nut lol. Didn't find anything else wrong with the car. It's not skipping, idle is fine, runs smooth and no codes. I told them to do oil change while it's there. My son isn't gonna be happy!

 

So we have the cavalier in the shop now. Help me to clear up what he just told me. Car makes popping sound when you let off brakes. He said something about "motor mount"? Leaking hydraulic fluid? I will know better when we pick it up. It's $200 fix. What was he saying it was? lol

 

I believe that 2.0 had a front hydraulic motor mount. If the engine was moving too much it may have pulled a joint a part in the exhaust. Back firing on deceleration can be cause by fresh air entering the exhaust system near the motor.

 

Front hydraulic motor mount is exactly what they said. Why did it happen when I picked it up from there? It didn't do that until they changed the tires? So you're saying that was backfiring I was hearing?

 

I think I may have figured this one out. We had the oil switch and belt replaced. Would they have messed with this part? Maybe raising/lowering the engine to change those?