Car idles at 3500 RPM!!! What is going on here?

I drove to do some community service this morning and after I got on the interstate, the revs wouldnt go down. I had to turn it off at every light and no give it gas when driving( its like a permanent cruise control). What happened? Haynes says it could be a sticking cable( but it moves fine), a vacuam leak( still pulling plenty of inches of vacuam) or a fuel system or engine control system problem. What else? Eades suggested TPS mighta died on me. Im gonna go check that now. Any ideas? I need this car for prom next weekend!

Ok jsut played with it a little. That little stop on the left hand side( when looking down and from the front of the car) on the TB, is that a good way to adjust the idle? I thought that the EEC controled the idle and no matter what you set that stop at, the EEC would change it to its needs. I adjusted that stop and it idles at 700 now. I think maybe when i was cruising on I 95 maybe when the TB was open, the lil stop rattled its way down so when I closed it after I got off 95 it only closed so far. But then that wouldnt explain why it idled at 3000 for a little and then 2000 and finally at 3500. Whats a good idle speed for a supercharged car? It used to idle at approx 850 but the supercharger is really really loud at that RPM so a little lower would be nice but I dont want to hurt anything.