we have a 03 5.9 diesel. when we pull our gooseneck horse trailer we dont seem to get the power going up hill and it seems to surge. Ive changed the fuel pump,fuel actuator and the lift pump and it seems to be worse now. It runs fine when its not under load. Ive been told it could be the injector pump or the torque converter. anybody got any ideas?

 

I have an 03 and just replaced the tranny, my surging is now gone.

 

There is a TSB may solve your problem.