at a cold start it idles at around 2500 and when its warm it idles around 1500-1800. and sometimes it fluctuates when its warm temp and at idle only. fluctuates around and jumps from 1000 to 2000. i tested my iac by unpluggin it while running and it suppose to drop down to 450 but still idles around 1300. i think my iac is that cause but just wondering if anyone else ran into this problem and it not being cause by tha iac. also my idle screw adjuster is all tha way closed. any help would be greatly appreciated. thanks!

 

I had a very similary issue and it turned out to be a vacuum leak. Spray carb cleaner around all vacuum hoses and sources. If the engine rpm changes, you've found the leak.

 

The last time I had idling issues is when I had a vacuum leak some where on my intake manifold, and when a rebuilt my motor and was getting it tuned. I had to take it back to my tuner to adjust the idle since it was pretty erratic when I got my car back.