Since your cold idle is ok, as long as it's not because of a vac leak, the IAC might be fine.
If you clean an IAC, be prepared to replace it. Sometimes cleaning makes them worse or wipes them out.
The opinions of others will vary. I like to soak the guts with WD40 (fill it and let it sit for 15 mins. Dump and repeat a few times). Follow that up with a cotton swab cleaning (non-linting swabs - you don't want to leave lint in there) and then I spray it out with electrical contact cleaner.
You might wanna make sure the ECT is in calibration at higher temperatures first.