Thanks for the fast replies!
It does not surge, it just shuts off as if you hit the kill switch!
I tried pushing the kill button (the one I use to heat up the glow plugs) but got no response or flashes from the light on the start and kill switch (there is a blue light on the switch but no blinks).
Of course, I just went out and ran it for 15/min. with nothing turned on; it didn't even get warm. Then I turned on both air conditioners for another 15/min. - it ran fine, no shut down and as cool as if it had not been running?