Are you sure your ECU is from THAT car? If you have a 5-speed car with an ECU from an automatic, you would have that problem. There's a thread on it. You'd have to remove RP17 and RP18 from the ECU. I did that, and the up and down idle VANISHED! Good luck. In addition to that, I cleaned the heck out of the IACV with carb cleaner. It looked like the bottom screen of a pipe before I cleaned it.