My 1999 GT is idleing rough. I bought the car for its original owner who had put a 75mm throttle body, air intake, slp exhaust, shorty headers, bbk x pipe with cats on it. WHEN THE A/C IS ON THE CAR IDLES PERFECT. Im not sure if I need to adjust my airfuel ratio or what but its odd that the car runs better when the ac is on. any advice is much appreciated. thanks