I bought a '94 Pathfinder with 90,000 miles in decent shape a few months back. Everything was fine until a few days ago when at 3000 rpm at every gear there is a high-pitched squealing obviously a belt. The engine in general sounds a lot louder and higher pitched since this started happening as well. I'm a student and don't have a lot of extra cash and would rather not pay someone to do what I could probably do myself. I'm guesing it's probably the timing belt, but before I go and order another I wanted to hear what you guys might have to say. I appreciate the help and any advice.

T-belts don't make a squealing noise when they go bad. It's a slapping or fluttering noise. Are you sure it's a belt and not an idler? Try spraying some wd-40 or silicone on the belts one at a time and see if the noise still persits. Or you could just take them off one at a time and see if that does anything. However if your vehicle is still equipped with the original t-belt, then change it now along with it's tensioner.

T-belts don't make a squealing noise when they go bad. It's a slapping or fluttering noise. Are you sure it's a belt and not an idler? Try spraying some wd-40 or silicone on the belts one at a time and see if the noise still persits. Or you could just take them off one at a time and see if that does anything. However if your vehicle is still equipped with the original t-belt, then change it now along with it's tensioner.
To be honest I'm not really sure of anything. I have relatively no mechanical experience. What exactly is the idler? Isn't it somehow related to steering? Whatever the problem is, it worsens with higher rpms.

The idler I was referring to is, an auxiliary pulley that the belt rides on that is not a component ( IE: pwr steering pump, alternator, etc.) What do your drive belts look like, are they starting to crack or is the back side starting to glaze or look shiny? You could also have an accessory pulley/bearing going bad, which is causing your noise.