try replacing the two smooth pulleys on the front of the engine mine did the same thing almost sounds like a supercharger whining.

 

I've already changed the belt and idle pulley and tensioner. It is definitely not any of those.

 

Check the air filter and piping going to the throttle body, almost sounds like it is starving for air. A loss of power with no CEL could also be a transmission problem. A long shot could be your coverters are starting to clog and too much back pressure has created the whine.

 

but my truck is still making the daggum whirring/whining noise...
Start the truck, start out going down the road:no noise
Go about a block and once you get to 1500rpm: noise
Its a constant noise once you get to 1500rpm and go through the gears until it either goes into OD or you let off the accelerator (both dropping under 1500rpm) Any fresh ideas what the heck this could be? exhaust leak? tranny probs?

If it was a bearing, wouldn't it have gone out by now? (its been making this damn noise for 2 years now)

 

There are several threads from guys on here (and some YT vids too i think) of the trans making a whining noise

 

So it goes away when you coast without the accelerator?

 

Only whine ive heard like that was from 06 4x4 Night Runner terrible power steering whine

 

It doesn't completely stop, just quiets down enough to not be noticable...

When the truck's cold there's no noise at all, but after about a block, once you get to 1.5k rpm it starts whining.

I'm thinking of checking the exhaust this weekend while I'm under the truck changing the oil.

Also, the truck doesn't run any differently at all than before the noise started occuring, its just annoying and sounds HORRIBLE.

 

I used to get a whining or whirring noise, was there 80 percent of the time. Turned out to be the bearing in the alternator.

 

I'm getting the same noise, seems like it started after I cleaned/degreased the engine bay. I was thinking maybe the degreaser got into something it shouldnt have. I'm kinda thinking it could be the fan clutch, just not sure on how to check for sure without just starting to swap parts out.