This is an old issue that only comes around every couple of years for me.....I finally figured out that its only around when I put my stock cat in for smog tests! When I first got the evo, used, I had to smog it. It drove great the first week, and I put the stock cat in I got with it for the smog test, and the tester couldn't keep the car at the necessary 2500rpm. I thought he was a moron so I went under hood and tried to do it by hand. No dice. WTF? It would go up over 2500 to 3k, and dip back down to 1500, and oscillate between no matter how little I moved the cable. I passed smog because the tester just rode the clutch to get the 2500 rpm with my OK, which induced load, but I passed.

Recently I installed the stock cat again, and noticed I couldn't hold 2500rpm? I checked around on the throttle hang, idle stepper, threads, but none of it seems to apply. Any ideas?

Mildly tuned, stock turbo, stock cams.

Thanks!
M

 

Anyone ever figure out a solution for this?? I'm having the same issue.