Stock GT that runs great with 58,000 miles, auto, 22.5 mpg. Idle is fine with out the A/C running. Turn on the A/C and the idle will sometimes jump to 1500 and down to about 400. Cruising is also bad with A/C on. I can feel the surging while on cruise control, on level ground. Feels like a strong, gusty head wind hitting the car. I do not see a change in the tach or speed while cruising. A/C clutch is NOT kicking in and out during this. I guess it is not the IAC as it is bad at speed also but..... Any ideas?