Hello this is my first post here but i have been coming to the site for a while. The other day i was driving down this pretty cruvy road pushing some high rpms, well when i got home i let my car idle in the driveway why i went and got something out of the house. When i came back a few seconds later my car was idling all over the place jumping up to about 1500 then going back to about 900 rpm. Ever since then it does that in idle when the car is not moving, but it dosn't do it when my car is out of gear and im coasting down the road or when the ac is on. I have a 93 prelude si with a aftermarket intake(rs akimoto), if anyone can help me fix this problem let me know thanks alot.

 

Vacuum leak perhaps. Someone just posted recently about having an irregular idle as well.

 

no check engines lights are on

 

Are you throwing a code? Yeah if it's a pulsing idle it coulde be vaccum. It could also be your timing, or just need to clean out your throttle body.