I chased down a similar problem in my F2K. Mine would work for an hour or few minutes the reboot. Testing all voltages, could not find the problem.
I took my Fluke meters that record ( min/max) function and clipped on the the power feeding the MPU. Turns out the 5 VDC was dropping for a few milliseconds and coming back. I changed solenoid driver boards and the problem went away. So I have 1 more board to work this Winter.