When you say it runs out of drive..What does that mean?..Does it stop & will not move or does it seem like it is low on drive power?..some d3g had problems with sticking decelerator cables, not allowing the engine to reach high idle speed. Check to see if when the machine acts up, you're not reaching high idle. High idle speed should be 2400rpm t/-40 rpm. Once the engine speed starts coming down the ECM starts to destroke the hydrostatic pump because it thinks the engine is being lugged. There was also problems with sticking spools in hydrostatic motors... but that normally caused only one track to die out, never seen both sides stick at the same time, but i suppose that could happen.