I have a 2003 TL-S and am having problem with my idle. My idle goes between 500 and 1200 at idle when I have the air or heat with blower on. It stays pretty steady with them off. It doesn't do this when I first start engine but after it reaches normal operating temperature and I turn on the air it will start to fluctuate. I have change the ICAV twice from Orielly, clean the entire plenum checked all spark plugs and coils, changed all motor mounts and still doing it. No check engine lights, anyone have any suggestions?

 

vacuum leak