fast idle- need help!

Hello! I've recently "inherited" a 1991 Jetta (gas engine, automatic). Runs like a champ (though I never thought I'd own an automatic trans-- in a VW, no less! It's almost treasonous!) except for one problem I've not been able to run down. It has a very fast idle. Smooth, but always ~1800rpm. Regular idle adjustment does *nothing* to lower the idle speed. I've given a cursory look at the vacuum lines but thought someone here might be able to save me some frustration :banghead: and time. Grew up in a multi-VW family, so I'm pretty well versed in the older VWs. I definitely need some education on the newer FI and specifics of this model though! Too bad it's not a good ol diesel... thanks for any ideas or assistance! --Jim B., Cleveland OH

There is an idle valve right in front of the valve cover, its about 1.5" round & 6" long with a 1" hose coming in one end & out the bottom. Clamp off the hose in the end when it's warm & see if the idle drops, it shouldn't. It could also be a vacuum leak. Is it a 1.8 or 2.0 (16 valve)?