I have a cold idle problem on my 05 Evo. Mods are cams, throttle body, TBE, cat delete, drop in filter. A WORKS 340 package. The mods have been on for well over a year. The problem has only recently surfaced. At startup the idle will go to approx 1800-2000 rpm. Sometimes it will drop slowly to 1500 rpm. After the car warms then the idle will drop to it's normal value and everything is fine. Really its just annoying to have the idle go high for three to four minutes until the temperature comes up. I did check the Idle air stepper motor as far as the resistance checks. All ok. I even took it to the dealer recently, who by the way never said a thing about the mods, and he said they checked everything and all signals, etc. looked good. I am just wondering if they didn't check as thorough as they should have. My thought is to just go ahead and replace the IAC stepper motor and see if that works. Any thoughts would be appreciated. Also how does one perform the boost leak test that often gets mentioned.

 

I got the same issues and now when I turn on the A/C the idle drops down real low. sometimes stalls. I have an AEM and 2.3 stoker. I am replacing my IAC today and will see.