The track motors on my ex120 go slow but when I use another function especially the tilt function on my tilt bucket the track motors speed up any ideas.
I'm sorry, I am unable to help with this.
The electronics on these machines can be a PITA. I would first check the pilot pressures to see if you have the correct pressures on that system, both regulator and control. Then check for the correct pilot pressure output from the travel pilot pressure control solenoid. If these all meet specs, then there are two switches on the travel control valve (right side facing front) which tell the PVC to increase flow in response to the travel demand. Check the wiring connections first, then check the operation of those switches under travel load. Sounds like the main pump is not being told to spool up to adequately serve the travel motors, but the other control inputs are telling the main pump to spool up for the load.