Something wrong with 5sfe..?, ..what is this swirling sound? Options

[LatinKraze]

This noise started last night. I know I pushed my car twice to 5k. I was showing my cousin the art of 5spd. Well anyways. When I dropped him off at his house I notice that (in 1st, 2nd, and 3rd gear) I get this pulsating, hissing/swirling sound at around 3.1k until I shift to a higher gear. I pulled over immediately and reved my car by hand, and no sound. It seems to happen when I'm in motion. The noise is almost like taking a rope and twirling it real fast to get that almost whistling sound. Has anyone else had this happen? I cant seem to narrow it down to where it's comming from, since I'm the one driving. It comes from the passenger side and I dont think it's any of my belts. Any suggestions?

[WannabeGT4]

If it's not vacuum, you might check your alternator. Put a volt meter on it and see if the voltage is fluctuating, or take it to Autozone or whatever you have there and have them test it. If you have a smooth idle and no loss in HP/Performance that'd be the next thing I check since it's so simple to replace. Then I'd check your idler pulley then your pumps.