Jeff it depends on the control system,and what else is happening. Do you know the serial number? Does the unit throw a code when this happens?

I would be suspicious of the deadman pedal/switch and control handle.
Its possible the switch is cutting in/out or is damaged or the wiring to it is damaged. Same with the handle in most models.
Does it sound like the motor is disengaging when this happens? Maybe a
tripped gear?