I have a 2000 Alero (100K+ miles) and I too have a fast idle issue. I've taken it to the dealer and they can't figure it out, but what's new with that. Past posts have indicated a dirty Mass Airflow sensor, excuse my ignorance, but what does it look like and where is it located?
TIA

I see you re-posted which is better because you have a 3.4L engine. The other thread was centered around the 2.4L 4 banger.

It could be the MAF sensor but other things will casue a high idle such as a dirty or defective idle air controller (IAC), vacuum leak or dirty throttle body and IAC.

What are the rpms reading at idle?

See pic for MAF sensor location, circled in red.
http://i5.photobucket.com/albums/y186/lizzywiz/alero_maf.jpg