93 explorer vibration noises

I have a 93 explorer with loud vibrating noises at high RPM. The sound could be compaired to a loose heat shield on the exhaust sytem. But I have removed all the heat shields and rulled out that possilbility. Would appreciate any help with this problem.

Is the noise only when the vehicle is moving, or can you duplicate it in park/neutral? Can you tell the approximate location where the noise is coming from? Is it only related to engine speed or also to vehicle speed?

-Rod

The noise is only when the car is in motion. The sound comes from the front end, towards the center. At first I thought maybe it was bearings from either the water pump or alternator, but both of these parts are new. The sound is not related to vehicle speed, only the RPM of the engine (between 2800 and 3300).

I'm suspecting then that it's a bad bearing or bearings in the idler pulley and/or tensioner pulley.

-Rod