Very high idle?

Had a strange thing happen to me this morning. I have an 01 Grand Am with the 3400 in it. It seemed to be running normal on the way to work, but after my 30 min of highway driving, when I came to a stop at a stoplight it felt like my brakes were having a difficult time stopping the car. I was a little concerned, but it wasn't that bad. When I got to the next stoplight I noticed it again, and this time I noticed that the tach was reading 1500 RPM's at a complete stop. That was strange. I put the car in neutral and the engine revved up to 3500 RPM's by itself. I pushed on the gas pedal and it was responsive, but it wouldn't rev/idle normally. After I got to work, I turned it off and then started it again and it idled normally. Any ideas as to what happened? I'm hoping for a fluke thing, but something tells me that with my luck it's going to be a pain in my rear.

- clean IAC valve
-inspect IAC wiring and connectors
-replace PCV valve
-test for pending codes

thanks 3100, I'll give all that a go when I get home this evening. The PCV valve is fairly new (within the last 6 months) but I have been having an issue since my origional PCV elbow cracked, all the replacements I get seem to melt a hole in the outside of the elbow after a month or so, it's been a pain. I'll check out the IAC valve and make sure it is cleaned.

I had a bad throttle position sensor on my 2002, it was doing the exact same thing you describe.