Just in the last couple of days, everytime I downshift I hear a quick sqealing noise. It sounds like a belt. Just 1 time it squealed for about 5 seconds then stopped. I haven't driven it since, what belt should I look at? What one would be the one making the noise during downshifting? It will not do it by just revving the engine so its hard to tell which one is doing it. Does not make noise any other time, just on downshifts. They are all preaty new, probably just an adjustment issue.
Thoughts?

 

Check/adjust tension on all of your belts. There are specs in the FSM. If you have the air pump removed, the alternator belt will slip much more easily.