the IAC is the cylinder lookin deal on the front of the TB (throttle body).
have you pulled codes yet? i bet JR will provide a link or 3 for ya, if you need them.
He is an EFI guru.
give any info that you can. so it revs ok with no load (idling). do the symptoms change when you floor the pedal vs accelerate moderately? stuff like that.
i havent pulled codes because the check engine light is not on. the only other info i have is it has a hesitation in park and then revs ok. sometime it will drive ok for a minute and then start the symptoms again. just goes to 1500 and stops until 1000 then its like it just wakes up again and goes.
even if the CEL is not on or has not illuminated, a code could have been tossed. the code would be in the KAM. if you have a split second malfunction, it could not touch off the light, but pop a code. worth checking, IMHO.
you are losing me: if i read correctly, you said it does not hesitate when revved in park. then you said it does hesitate......
i would check out the TPS as everyone else mentioned. if there were certain situations where the issue did not occur, i might have looked past it. but it sounds like the problem may be there pretty often....checking the TPS takes 5 minutes and voltmeter (analog is preferable).
check for a nice even sweep in the return voltage from idle to WOT. there should be no breaks or drops. voltage range should be ~ <1.0 volts to ~4.5 volts.