Recently acquired this truck with a vibration from the motor. I initially assumed it was a balance issue. I replaced the harmonic balancer with a new one, and even with no belts attached still vibrates. Idles fine but as soon as you start to rev the motor, it vibrates exponentially to nearly a teeth-chattering experience. I even pulled the clutch/pressure plate out--no issues there. I'm beginning to now think it's an electrical issue. The only code I've seen is a P0155, but I don't think this would be such a drastic engine vibration issue. Much appreciate any ideas where or what I could possibly look into now!