I have a 99 Dodge Ram 2500 Diesel 4x4 (240000 mi)with an automatic transmission. The problem I am having is that the 4th gear lockout does not disengage. When I put it in gear it is like trying to move in 4th gear. It stalls a lot. I changed the lockout solenoids and it has not changed. I rerouted the coolant lines to see if that was the problem and it is not. Do you have another suggestion?