Squealing from under the hood under power

Okay, so I just replaced the battery and the alternator on our car, and already had a slight squeal for a few seconds when you first start the car but then it would stop. Now after the noise stops, when you put the car in drive and start to give it gas it starts squealing and does not stop until you let off the gas. All the belts are tight and none of them are shiny or cracked from what I can see. I am just wondering what is more likely to be causing the squeal, the belt tension-er idler, or one of the other two belts?
I plan on figuring it out today one way or another, but I wanted another opinion just in case I am missing something.
it is my opinion that the tension-er idler bearing could be dry or have some dirt inside it, but I am hoping that I can just soak the bearing in transmission fluid for an hour or so, pull the side off the bearing and spray some lithium grease in there, replace the side of the bearing and reinstall the whole thing back on the car. Hopefully that will take care of the squealing until I can get a new tension-er idler bearing or even the whole bracket assembly.
Again thanks for the help