No matter what I do I can't find what's causing it. Only at idle, or slowing down while driving(coming to a stop). Motor mounts look good I also have a torque strap. My air fuel ratio is good. New wires new ignition.
Wouldn't an out-of-balance rotating assembly cause a vibration that gets worse as the RPM's go higher? Does it vibrate in neutral if you slowly rev it up? Sounds more like a timing issue, or maybe you have a loose plug wire or two of them are swapped?
I agree with 66340 though stock damper is pretty weak for a healthy 408.
