My bonneville doesnt squeal all the time, only sometimes, but when it does it squeals like a HIENA!! It drives me crazy! It goes away when i accelerate but as soon as i let off the gas, it starts again. But like i said, it doesnt do it all the time, around 50% of the time. Please help, any suggestions! By the way, belt dressing didnt work.

Can you tell which side of the car it'* coming from? Does it happen only when in gear?

It sounds like its coming from the belt area. And yes, it does it when in neutral or park too

You could have a bad bearing on a idler. I would start checking those over. Also check the water pump and alternator, these can squeal.

This is probably a dumb question, but how would I go about checking all these?

Take the belt off and turn each by hand. They should turn freely, no binding, no wobble, no gritty feel.