Just in case you guys havent seen the home page yet, check these Mustangs out that were seen at SEMA.
http://www.stangnet.com/Ford-Mustang-News/2006-SEMA-Mustangs-pictures-061031.html
Many more to come...
I wouldnt buy a new IAC if cleaning it didnt help. You can usually tell its a bad IAC by cleaning it, and it will temp. fix the prob then you know its bad IAC.
Take the IAC off, clean it with carb cleaner really well. Then reinstall it, if that fixes the problem, then you know the problem is the IAC. Then you can get a new one.
Update: Resetting the ECM didnt do anything for it. Im going to see if the gasket is one backwards. Im scared to seafoam the car with this many miles on it, I would be PISSED if I seafoamed this car and it started burning some oil...What is the restrictor plate you speak of?
Do you mean the stud is stripped? If you, to get it out, you're going to have to double nut it probably and use some vice grips to get it out. Its going to be a pain in the ass. I promise. Do a search on here for a Prochamber stud replacement.
Yea, Id say have them rebalance, if its not right still, take your money elsewhere. I had one of the bigger shops in town install the tires on my bullitts, and it shook like mad, took it to a smaller shop, smooth as glass.
You can always make your own as well.
http://forums.stangnet.com/showthread.php?t=400696&highlight=homemade+mil
Otherwise, Id get the plug and play ones that cost a little more.
A shorter, straight to the point version can be found here.
http://www.planetmustang.com/aftermarket/shelby_gt500_at_700hp_with_roushcharger_000969.asp
Its going to be awesome with 700 hp available.