My car just came from the shop a few days ago. I had the timing done and replaced the A/C compressor. The guy who did the A/C told me that the vacuum solenoid is not working properly. As a result, every time I turn on the A/C the rpms drop bet. 750 to 1000 rpms so he set the throttle at 2000 rpm when the A/C is off. The thing opposite the throttle is what the mechanic says is faulty.