I have a 99 se 5-speed and I have been having a weird idle issue. Randomly when I put the car in neutral or just push the clutch in the car will rev to 3000 RPM and stay there. I will put car in gear and go and the car will continue to do this in neutral or with the clutch in until I turn off car. As soon as I turn off the car and start it again the idle. if fine. No codes thrown either.

I was thinking maybe I IACV needs cleaned.

Any help is appreciated.

 

Defiantely start by looking at the IACV. Even if it's not thrown a code yet, if your problem continues I'd replace it.