So it's been happening for a while but never bothered me until after I swapped gears. From idle (like at a light), as soon as the engine has a load, my rpms drop a good 1000 or more, then goes back up and continues like normal. Also, if I power brake to try and get my tires loose or lock the rear end, it just sits and fluctuates 500 rpms and the tires can't break. All the maintenance factors have been checked ie throttle body cleaned, spark plugs replaced, air filter, etc etc. I should mention it ONLY happens when the engine has been running for a little while (1 hr+) and is warm, otherwise it doesn't do it. I was thinking a sticking IAC but I figured other opinions couldn't hurt.
Case in point at WOT