On the 4Runner, the throttle-by-wire throttle bodies have a non-swappable IAC, If it fails, you have to swap the whole throttle body. Not cheap.

 

Great to hear you solved the high throttle issue! Sorry to hear it was so expensive...

I had the same issue after replacing my valve cover gaskets and cleaning the throttle body, but luckily some MAF and IAC cleaning fixed it. My idle was up around 1,100 for a few months after that job. But after reading through some ideas in the thread here, I cleaned some things out that probably got jammed up with the carbon that ran out of the throttle body when I cleaned it, and the idle eventually dropped down below 1,000.

I'm at just over 200,000 miles now and everything seems to be running perfectly.