That almost sounds like a bearing that's on its way out. Could it be the belt tensioner or Idler Pulley?

 

It sounds more like its coming from the rear of the engine, I cant hear it near the pulleys in the front. Whatever it is it wasnt there when I started it a few hours later last night.

 

Pull the oil filler cap off and see if it quits

 

It sounds exactly like a really bad vacuum leak to me, that's whats weird about it.

 

I clicked the link to watch the video and it isn't there? It says "this video is a duplicate of a previously uploaded video"? I want to hear this noise...from the way you describe it (not following RPMs and staying consistent), it sounds like a vacuum leak somewhere...

 

hmm, try this

http://www.youtube.com/watch?v=SPUZ5Osyawg

 

sounds like its pulling a vacuum in the crankcase and the rear main seal is whistling.

 

Wow, that's definitely a high pitched ring! I have heard vacuum leaks that sound just like that though...funny that it went away, kinda like something was open then closed up...

 

I think it might have been the vacuum hose between the passenger side valve cover and the air intake tube, but all I did was pull it off and put it back on. I think it might have a hairline crack in it or something.