Hey! My car is making this loud schrill-ing noise. It’s a 90 S5 tii. I have a new air pump and alternator, and have had the air pump and power steering belts off while running. Still makes the nose.

 

Constant shrill 3000 rpm

 

Only makes noise when coming off throttle

 

Hard to tell from your audio clip, but that 3000 rpm screech might be the fan clutch and/or PS idler pulley. I've recently had the same problem on my S5. Every time I hit 3k or higher rpm, I'd get that annoying screeching noise. Remove the four fan bolts holding fan blades and clutch to the water pump. Then start the car and run for short time (10-20 sec), and see if the noise is gone.