Quote Originally Posted by dsmuts View Post
One other thing to check is the harmonic balancer they can over time wear out and make noises like that. Another possibility is flex plate but the noise ususally goes away when throttle is applied.
I had a knocking/rattle sound at idle and went away with any rise in rpm......thought it was the coupler, replaced that and no change. Took both belts off and still rattled......replaced the harmonic balancer and no more noise. Just fyi if your still trying to fix, or for anyone else who is the same boat on here