I understand about diesel engines needing to breath, I've got several. This is not a horse power issue, it is a matter of the horse power it has not going to the wheels. I would think I should almost be able to stall that engine if the wheels won't spin, and that is not the case.
Changing the hyd fluid may help, but they don't call for that before 100 hours. Are you all changing your fluid early to put in the other stuff?
It still acts like it does not build up enough pressure in the trans, I ought to be able to spin the wheels or bog the heck out of the engine if I can't spin the wheels, and I can't.
Wayne