my car revs back and forth from 1000-1500 rpms at a stop what do you think is the problem i just got a whole new exhaust,intake.plugs.fuel filter. I'm thinkin bad sensor i dont know which one tho? thanks for the help

 

Have you tried re-setting your ecu?

 

I saw a post a while back about some guys who were just swapping out their "ground" wires for thicker, better quality wires with nice connectors. They claim this stopped their engines from rev'ing like you describe. Maybe try that.

 

Well...this may be a bit obvious but check the vacuum line behind your intake manifold. It's closest to the driver's side, back of manifold, atleast on a 99 si. I was having the same idle problems and I noticed I knocked off that vacuum line, put it back on and viola...all good. Otherwise maybe a sensor like u said.

 

My friend had the same problem in his 89 accord, it's a real easy fix. What kind of car do you have?