My 99 honda civic si idles up and down while its parked. After I have driven it a while, while i am at a stop light it starts idle up and down so fast it sounds like its cutting out. When I try to slowly take off it falls on its face!!! If I floor it, its fine.... I just replaced the Idle Air Control Valve and I thought it fixed it, but its doing it again. The code is coming up as Idle Air Circuit Malfunction!!!!

Can anyone help? Someone said check for vac leaks but I dont know where to start with that!!

( by the way, it didnt start doing this until i sprayed cleaner into my throttle body, i was trying to clean out the carbon)

ANY HELP WOULD BE APPRECIATED THANKS!!!

well. you might hurted one of the sensors on the intake manifold. i had the same problem with my civic 95. i replaced the map censor. it is located on top of the throttle body . check if one of the vac sensor on the back of the manifold was loose or broken, but i almost sure is the map sensor.

sorry. i think it is too late.