My 99 Sport is starting to idle high at times, up to about 1800 rpm but only with the air on. This has happend a few times now and i am not sure were to start. Idle air control or vacuum leak in air conditioning system. Any ideas out there. I can turn the air off and it drops to normal 750 rpm. I have done this several time to make sure its not a fluke. Its a pain in the butt when you stop at a light.