I occasionally have the same problem as this lady here:
http://www.toyotanation.com/forum/ar.../169169-1.html
I noticed it about 4 years ago and it happened again in this last week. Thinking back, it seems to only happen around this time of year. Not sure if it is because we are travelling more, or the hot humid WV weather is doing it or what.
I don't think it is the IAC (But I'm not pro) as I do clean that out occasionally with some carb cleaner. I do that because it used to start yet idle real low with the possibility of quitting. I squirt some carb cleaner in the IAC at start and it opens right up and idles fine.
This only happens after driving for a while. At sometimes it will take quite a few attempts to get it to start again once it stalls out.
Thoughts, ideas?