Has anyone run into this problem?
Have a '92 Accord EX, just had front-to-back exhaust replaced about two weeks ago. Since then, in Park and neutral the car is "hunting"; alternating between 800rpm and about 2000rpm every 2 or 3 seconds.

Does this while driving as well, high idle (about 1500) while sitting in drive.

Tried replaicing the O2 sensor, we tried the codes with the manual but the "check engine" light doesn't come on.

(Did ask exhaust guy, he thinks this is unrelated to what he did.)

About to give up and bring it to dealer, thought Id give a try here...

Thanks

 

Sounds like a vacuum leak