hey All. My wife has been complaining that her 99 v6 5-speed mustang has been idling high. So i go out in to the garage and start it cold and it idles fine. And then she tells me that it does it when driving around in it. So i hop in the car and go threw some lites and get on the free way and nail it threw the gears and hit the next off ramp and slow down for the red light when i noticed that the rpms are staying at 3000 and then i come to a complete stop in neutral and it's still doing it then about 10-15 seconds later the rpms drop back down to normal so i take it home and inspect the gas pedal and throttle cable to make sure nothing was hanging up and it was fine. so im thinking maybe idle air controller. Anyone know? or any ideas that would help.

 

try cleaning the IAC.

 

what he said

 

i had that happen to me and it turned out the idle screw was loose