I know this is a newbie question--i just recently got back into the Mustang scene. But everyone of my cars ive had over the last 10 years have idled like crap when cold--i have to sit there and rev the motor up until it will stay at the same RPM. Is it the IAC?? Doesnt seem to be a vacuum leak--car runs and idles fine when its warmed up. Major Mods consist of E-cam and Longtubes and H-pipe--its a Speed Density but even my MAS cars have done this. Thanks.