What is the difference between TOWING mode and OD off. When I push the button one time on the end of my shifter it shows TOWING and when I push it again it shows OD off. In TOWING mode the RPMs are about the same as regular and the (vibration or slight shuddering stops). And when I push the button the second time it cuts the OD off and the RPMs go up and the issue also stops. Is it the lock up converter causing the problem?