Pull and remove your TB and clean it THOROUGHLY with a good TB cleaner. If you've never done it before, and this is the first time for the rig, I have found the dealer TB cleaner to be a little stronger and easier for a first time cleaning. On subsequent cleanings every spark plug change at 25K on my rig, standard Napa cleaner works fine. The difference is a couple bucks in price so the lack of time spending cleaning with the little more expensive dealer stuff is worth it to me for the "first time" cleanings. You'll need to scrub that thing thoroughly with an old toothbrush, and clean every nook and cranny on it. Excercise the plate and get all around it as well. You want a mirror finish with no dull grey/black marks anywhere, no rings, no residue. With that done, clean and exercise the IAC as well. Depending on what year/model you have, there will either be one, or two screws holding it in. Clean it thoroughly as well.
Prior to TB removal I'd suggest getting a new gasket just in case you have trouble getting yours off and ruin it. They're about $4.00 or so from the dealer or parts store, but make sure to get it ahead of time. I've found that none of the parts stores or dealers in my area stock this item. They get it overnight, but won't have it the same day. When I do this, I order the gasket a couple days ahead of time when I know I'm going to be cleaning it so it's here when I'm ready for it.
This is a good general maintenance routene that I do with every plug change. Keeps things clean and fresh inside with the TB and related parts working properly. This was the only thing that cured my erratic/slow responding idle problems in the past. I make it standard maintenance on all the family vehicles now, and have had good luck doing so.
Best of Luck
Mike