I have a 3/16" hole in my plug. There were never any signs of stalling, not so much as a stumble, even with full accessory load. As I say, it worked great for about two weeks of driving around town, but the first high-speed trek seemed to screw it up.
I don't think it's the IAC valve...mine had been sticking, and I had it replaced by the dealer about a week before the TH plug went in.
I'm going to put the plug back in a couple of days (when it stops raining) and reset the computer at the same time.
We'll see.
