when I turn on my air (not AC) to AC,Defrost, or Mix my car idles rough. If I switch to vent or Floor it's fine. It doesn't matter what temp the air comes out at, it just seems to be the diff. in setting. No obvious vacume leaks and the car runs great if you dont pick the wrong selection on the climate control.
Mods are simple bolt ons ie; CAI,OFF RD. X,sct2. Talked to Ford Mechanic and he said to pul off the PCV valve while the car was running to check for vacuum, and I did, it had vacuum but the car ran like crap w/ it disconnected ---no shocker there but then after re-attaching pcv , my ac did not blow cold anymore and my low mile 2000GT still runs crapy when the air is on.