I have a 93 civic and it surges really bad at idle. It will surge from like 1500-3000, and it keeps going up and down till you start driving. I replaced the throttle positioning sensor, and the idle air controller, and they didnt fix the problem. What could it be? Do i possibly need to have the ECU reflashed or replaced?

 

check the FITV fast idle thermo valve. search it and you will find the easy fix