I have also had these models do this when the governor has got weak, put a tach on it and see if the rpms die off under load when you deadhead the hyds. Try to adjust governor and see if it gets better. From my experience if it changes it wont be 100 percent so you will need to install a new governor. This is of course after you have verified your inching pedal cable adjustment is correct. I hope this helps. Good luck.