I do not know what your noise is, but revving to 3000 rpm is not going to fix it for sure.

How many miles on the engine?

 

 

Is this the original engine or rebuilt / replacement?
There are literally dozens of possible diagnose. Without further insight it's going to be tuff give the correct information.

 

its the original engine. I can see if I can record it and upload it here to give you more insight

 

sorry for the delay, here is sound clip of the weird noise.

 

 

Sound file didn't work for me.

 

 

Sound file plays for me but is just a bunch of background noise. You've probably spent more on the alternator than you would pay for professional diagnosis. Having said that - my first step is to remove the drive belt and run the engine without it for a moment (not TOO long as the water pump isn't turning). That eliminates the alternator, water pump, etc. as possible culprits. I've even found cracked accessory drive brackets creating a rattle that you would swear were internal engine noises! Another possibility is a cracked flywheel. Holding the brake in drive and applying some throttle without allowing the vehicle to move (power braking) will load the flywheel - if the noise goes away it's possible that the flywheel is cracked or the torque convertor bolts are loose (very possible if the transmission was recently removed and reinstalled). If you're running the I5 it's possible that it's time for a new timing chain and guides. And don't overlook the balance chain and guide in the back of the engine block. I recently replaced mine due to a buzzing sound. Keep in mind that's it's not easy for anyone to diagnose engine noises without hearing them as one man's knocking sound is another man's tapping sound - or clicking. Or buzzing. Listen to the sound file again and rerecord if needed. It would certainly help us help you.