5 speed 2.3l....whenever the a'c is running (i guess bringing down the rpms?) and the clutch is out in nuetral, the engine will rattling pretty violently. When the clutch is pushed in it almost goes away immidiately. Since then the tranny was rebuilt, new clutch, new pilot bearing, and a new throw out bearing, yet the noise still remains. I drove the truck pretty rough and someone pointed me in the direction that it could be valve knock, and the only think the clutch pedal had to to with it was maybe putting the perfect amount of drag on the engine to produce that resonation of the engine. Has anyone had anything simliar to this?