I don't know, this is a weird problem. If the there was a short on the motor, I would check for loose or burned wiring, melted connections, maybe even have the computer system checked for any shorts. I betcha a nickel that your problem is electrical. My cousin had me drive her car to see what was causing it to jump really bad. I told her it might be the clutch going. It felt like it would slip, then grab, it was that violent. Turned out to be a fuel delivery issue, some shorted out relays.