Hey everyone!

I have a prelude 2.0 si from 1988, still kicking ass.. but now I've had to replace the original alternator (yes, believe it or not) and immediately right after, my car has a revving problem when idle.
For example, if you sit idle at a stoplight, it's revving between 1500-2000 rpm, constantly up and down.

Now, when you do run the car you don't have such issues with the revving rpms. I need to know what it could be. I don't think it has anything to do with the new alternator, but any suggestion would be appreciated.

I've read the boards, and people seem to say it's a vaccuum hose, but if that's so, where, and how? Little more insight would be good on this thing.

Any help from anyone would be fab, and you guys can e-mail or message me.

Thanks!

V