My Dad has a 65 coronet with a 440 and 4-speed. he has a vibration that almost feels like a missfire. He literally replaced and checked everything dropped oil pan no metal shavings did the clutch new u joints. all electrical etc. About a week ago he found a bent pushrod. Replaced it thinking it would be the problem. It still vibrates bad. Heres the thing it can be felt in neutral when reving the engine . Comes on at like 1500 rpm I think he said. Any ideas would be appreciated. He is at wits end. I would have thought it could be a bad ecu or distributer. He replaced it all.