Hello, I have a 99 Cobra and I have recently noticed what sounds like a grinding noise when I hold the RPM's steady, accelerate very slowly, or back off the throttle (as if you were holding 3500 RPM's and let off the gas peddle, slowly accelerated, etc). It occurs at all RPM's until the car is warm, then disappears. The car has a BBk intake, 62MM throttle body, x-pipe (catless), magnaflows, B&M short throw, drive-line specialties complete rear-end build with 3:73's. I want to let everyone who may read know what is done to the car in case it makes a difference. I consider myself mechanically inclined, but this is my first 4 valve 4.6. My first guess was throw out/pilot bearing? But it sounds like it is coming from the motor. The noise is present when the clutch is engaged or disengaged. The only thing that affects the noise is the car warming up. It had sat for awhile as a weekend driver here in Michigan. I thought the throw out bearing may have siezed some how or something wierd, I don't know, thats why I'm here. Car has 44,000 miles on it. Thanks for any help you may have to offer.