it's hard to say..but try start by cleaning your IACV.

i got my car back from the mechanic anddd...they couldn't find anything wrong.:bash:
they did the smoke test, didn't see a leak anywhere.(i can still hear a hissing sound)
sprayed brakleen here and there..nothing happened.
eventually the fluctuations stopped and then idle was steady, though still high.
it hasn't been acting up since then so..looks like we'll just see when it starts acting up again.

any ideas?

well i also hear a hissing sound... at first i thought it might just be the custom headers/straight pipe that came with the car when i bought it... my idle is normal its just that sometimes.. and not that often actually... that it kinda start fluctuating... at first i thought it might be the maf sensor? maybe not letting the ecu know how much gas to send? but idk cuz i remember fixing a family member's Camry lol and i fixed a similar issue by cleaning out the air temp sensor. so yeah idk... kinda clueless to what this might be

hissing sounds usually mean and air/vacuum leak somewhere..

and that would most likely be the cause of the fluctuating idle .... idk this is weird because its not an everyday thing... so hmmm..... could it be the air temp sensor?

i been dealing with same issues outlined here as well. what i can say is i just removed my AIVC (the system on the header side) and for the last week it just seems to idle and rev much cleaner, no lie. i have sohc with k&n drop in filter/headers/test pipe as my only mods. i do also do sea foam on a regular basis as well. gl everyone.

yeah, i seafoam once a yr, use fuel system cleaner every other oil change, do a wipe down of the throttle body and etc every yr.. have NO IDEA about the idle though. loll
I have a new egr system because i needed to pass smog(with a new magnaflow cat).

I'm just going to go ahead and replace all the air/vacuum hoses and hopefully that fixes something..lol.

+1 on the EXACT same issues, except i didnt take mine to a mechanic :p
anyways i havent thaught about the air injection system ill check it out soon, lets get this sorted out!

i changed my throttle body and that fixed my high idle.

driving-wise; it feels inconsistent. like sometimes, she'll pull hard. other times, she'll start bogging and just feel like crap.
i feel like theres a leak in my egr system..going to have to check that out later when i put on my new headers.

I would change out all the vaccum lines. It's cheap, just really tedious to do it. Do them one at a time to make sure they're hooked up right and look for loose electrical connectors or frayed wires while you're diggin around in there.

If you get lost or find missing vacuum lines there are plenty of decent line diagrams on the internet if you search google for them.