hey guys i dont know whats wrong with my 04 mustang gt but when i start the car up it idles at 3k and doesnt change also if i try to go along it stalls when i brake.. help !
The p1000 code means that the monitor test isn't complete. I don't know why it would throw this if the IAC is bad but your symptoms indicate a bad IAC. Someone with more knowledge will probably chime in soon. If it was my car I would probably change the IAC and see if it fixes it, if it doesn't then you have a spare IAC for when it does go out, and it will someday.
To test if its your iac.... Simply unplug it and see if your idle changes. If no change, its for sure your iac. If it does change..... I'd look for a vac leak.