Some times when I start my car my belt will be squeeling and when i start to take off the car doesnt want to go. The rpm dont go up and start to hestitate and sounds like its about to stall out. Evantually it will start to accelerate and when im driving my belt will start to sqeel real loud when I accelerate and then evantually go away. Also When I use my a/c the rpm hesitates and doesn't want to go up. I dont think its my a/c pulley tho cause when i use my heat it happens also. Possibly accessory pulley?

 

Could be as simple as the belt.that's the cheapest place to start. Also try starting it up and pop the hood see if any of the accessory pulleys are making any noise or maybe not rotating correctly.does it squeal all the time? Hot or cold affect it.examine the belt for damage or wear remove and look at pulleys and try spinning them all should spin freely minus the crank obviously.let me know what u come up with.
Ryan

 

In addition to checking the belt you should also check your belt tensioner. The spring in it may be worn out and not keeping your belt tight enough causing it to slip.

 

Don't forget that your AC compressor comes on when using the defroster.

 

i recently replaced my belt and the tensioner. After i changed it is when this all started to happen

 

have you checked any of the other accessories yet? i know of someone who had his engine replaced 'cause he thought the engine siezed while he was away. it turned out to be a siezed PS pump.
i'm not sure why your truck is sluggish, and why/how it's related to this squeal, sometimes the wierdest s**t happens.
we've (my brother and i) rebuilt the alt twice, replaced the water pump twice, changed the tensioner with ones we thought were good (from our stock pile), replaced the bearings in the A/C bypass pulley, and still have a squeal coming from under the hood. this is his show truck, and is only out for 5 months of the year, and this has been going on for 3 years now. when he touches up the engine bay this winter, i'm gonna do the crank seal-'cause i can't think of what else it could be, and everything else on the front of the engine has been done @ least once already!

 

I recently bought a neighbor's 2000 4X4 Blazer which was recently serviced with a new belt, tensioner, alternator and antifreeze. My old ears don't notice it but my kids told me the belt chirps. Long looks and listens at the idlers, etc. revealed nothing. Then it got loud enough that I could hear it with the hood up. The frequency of the chirp matched the belt rotation. It's the nomenclature (mfg's data) on the back side of the belt passing over one of the smooth idlers. So I ignore it.
On the other hand, if the chirp started with belt and tensioner replacement, are you sure the belt is on the crank pulley correctly? If it's "Off a tooth" it will protest loudly and have a very short life.
Good luck.