This could be a few things

[vtracer20]

Okay so i started up my car tonight...was around 0 outside...pretty chilly. My belt starts sqeeking, i just got them replaced (alt,power steering) like month or two ago. so i rev up the car and it sqeeks louder and at teh same time my car seems like it wants to stall out...the revs go all the way down to like 600ish. The revs went back to warming up levels after bottoming out. The sqeek is still there and after a few i rev up agian and let it go back down and the sqeek goes away. IT"S THE MOST ENOYING THING EVER. Plus i really dont think my belt are warn or anything...plus i've checked the tension and it seems fine. Any suggestions? Thanks

 

[luv2rallye]

Check harmonic balancer for separation. Otherwise tighten the belts more and make sure they are the proper width and depth.

 

[gsxboostin]

yes your Alt. belt maybe lose aswell as your powersteering belt

 

[Defiant]

New belts almost always need re-adjusting.

At least you're enjoying it.

 

[xcz504d]

Yeah, like defiant said, you usually have to re-tighten your belts after driving once or twice, also, I had a similar problem, I was outside at 5 am about to go to work and my belts were sqweaking, I grabbed my wrench and started to tighten the alt belt because I had just replaced it...

I tightened it about 3 turns, started the ca, same thing... I kept tightening the belt until I ran out of bolt to tighten it with and it still sqweaked... As I got frustrated I yanked on the belt real hard and noticed the alternator budged just slightly, I looked at the bottom side of the alternator and sure enough my pivot bolt wiggled itself loose...