Truck making a squealing noise

My 2004 Tacoma is making a squealing noise when when let up off the accelerator but is not consistent. I had the truck at the dealer today but they can't figure it out. Only thing that I had done 2 months ago was replace water pump and timing belt which they checked today and everything was fine.

Any thoughts appreciated.

 

Does it do it when your pushing the accelerator as well?

 

Sometimes, but very consistent.

 

Check all of you belts. Don't just look at them, feel the inside and make sure they are not starting to get a "glassy" feel to them.

 

I had the same problem and it wasnt the belts. (Search for my thread).

The only thing that i did to my truck before it made a squealing noise was a new power streering pump and a new muffler. It wasnt the belts, and it wasnt the muffler.
Someone told me to check my vaccum lines, I did. I also was tweaking underneith my truck and sprayed some WD40 on things that might have made that noise. Now i dont even hear it.
Try doing that.