I just did the IAC mod using a 1/2" copper plug. I drilled a 1/4" hole in it. My car idles @ 1500 rpm's now. The rev's drop quick but the idle is way to fast. What hole size should i go to next?? Does a smaller hole mean rpm's drop quicker. What about idle speed? Thanks

 

Start with a 1/8 inch hole and work your way up from there.
A 1500 rpm idle is way too high and I'd say the IAC is sticking open and needs cleaned.

 

Before the mod, the car idled @ 1k. Do you still think the IAC needs cleaned?? Or did the idle change because of the 1/4" hole??