not always the case though. it is a common problem. i had the same problem, was fairly hard to start in the morning. the idle would drop pretty low and id have to step on the accelerator a tad before it would jump up to about 2k rpm and then drop to 650. i cleaned the aac valve and it worked for a day or two then it started to happen again. i took the aac valve out to see if it were dirty but it was still fairly clean.
not sure what it is really.
ive tried unplugging the tps to reset idle, unpluged the ecu to reset every thing aswell but no luck.
but thats a good point, give the aac a clean and it might just work for you.