A faulty FITV could only cause a low idle when the engine is cold not hot. For a low idle when the engine is hot, start by cleaning the IACV. If that does not help, then replace the PCV valve.

Any CEL codes?

 

Air in the cooling system will cause an unsteady idle. With the engine cold, take off the radiator cap and make sure the radiator itself (not the plastic reservoir tank) is full to the top.

When you clean the IACV, be sure to clean the passages in the manifold that it attaches to as well.

If your idle is always too low, you could try opening the idle adjust screw on the throttle body.

 

Replace the IACV gasket/o-ring too if it is old and hard. You can ruin the seal when taking the IACV off and end up with a vacuum leak. If the seal is hard and you remove the IACV, it probably won't seal again once you put the IACV back on.

 

man i gotta write all this down! lol... thanks guys... before replacing any parts besides the gasket and stuff on the iacv, i'll check everthing ya'll said first... then i'll come back and reply on here and let ya'll know wat happens

 

also i just called the auto parts store... man that IACV i s NOT CHEAP!!! 205 dollars for that thing.... i said damn it!!!

 

what kind of engine do you have.this as nothing to do with your post just wondering

 

Looks like a d16z6 from his avatar but the pic's really small and I don't feel like clicking anything, so I can't say for sure.

To add to what ron said about the PCV valve, a quick check to see if a PCV valve is bad is to remove it from the car and shake it. If it makes a rattling noise, it's good. If it doesn't make a noise when you shake it, it's bad.

 

yeah i have a d16z6... i'm about to start workin on it...

 

ok just got done cleanin the fitv and the iacv... now its just a matter of time to see wat happens... i also checked my pcv valve... its bad! lol... but i cant get a new one now cause the auto parts store don't have any and have to order it...

 

i found an auto parts store that had a PCV valve. i replaced it and had to adjust my idle cuz its was loow... it idles good for now. just a matter of time to see now. plus it stopped goin up and down when the AC is on...