I have a 2004 FX4 ext cab with the three valve 5.4 auto trans. About a week ago I started getting a noise like a bad pully, but it starts at about 2200 rpms and gets louder the higher you go. It will do lt while driving on just reving in nuetral or park. at 5200 rpms it is just screaming loud. I had recently changed the tensioner, so I put the old one back on with no diference except belt squeal on high rpm shifts. I changed the fan clutch with no effect. You can not hear the noise outside with the hood up, but the engine makes a lot of noise normally at these rpms. In cab it sounds like it is comming from the passenger side dash. I tried 4x4 on with no effect. there seems to be no loss of power or performance. as long as the rpms are below 2200 you hear nothing unusual. all other pullies seem solid without the drive belt on, and as I said if I have someone rev it for me with my ear rhight at the front or side of the engine bay, I hear no unusual noise. Any ideas would be appreciated. Donald