My 2000 Eclipse GT 3.0L v6 makes a grinding noise at high rrvs/rpms (starts at about 4k rpm) it happens 9 days out of 10. when it does happen it has a lack of acceleration and power.

Use caution unless you positive your timing belt is in tip top shape. Interference engine. Valve damage will occur if belt jumps time or breaks. That being said. Where does it sound like the noise is coming from? Around the wheels, between trans and engine, engine itself or trans itself? How does the clutch feel?

Easy answer and fix I had the same problem . Belt tensioner/ idler pulley. It will make your alternator bearing go bad as well if you don't fix it and set proper tension on a new ac belt

Clogged air box or air filter. Guaranteed