Komatsu PC220LC-3 Engine Stalling

I bought this machine with a non working hydraulic pump, and put in a reman pump. The engine stalled frequently under normal operation. The new pump failed at approximately 200 hours. The instrument panel/monitor is not working. I am guessing that the controller and/or monitor are not working properly, and therefore the TVC valve is not de-stroking the pump. The people rebuilding the pump are saying it may be the main relief valve, but because of the electrical issues, I am thinking otherwise. Anyone have any knowledge to add? Any other thoughts?
Thank you,
Steve

Komatsu PC220LC-3 Engine Stalling