Lift playfield and look at wires going to motor. There is a red dot on one side of the new motor. That is where the black wire goes. The red wire goes to the other side. I put a new motor in and wired it red to red and had similar problems.
It that is not your problem, then maybe the cam wheel is not locked down with Locktite, and is slipping which is confusing the Optos below the motor. Clean the optos with a q=tip and rubbing alcohol.
Lets hope it is not a bad 10 Opto board sending mixed signals.