How about a loose ground going from the chassis to the engine? When engine torques up due to going in reverse or slowing down in gear it is breaking the ground circuit.
I think you are right and that could be the winner.....
The reason for this is that when I backed it up my driveway (in low low and it still kept dying cause its such a steep driveway) and since its under a load the motor is torquing ... I htink that when i back it up it does it mainly cause like you said it is loose and doesnt have a good ground and causes it to die...
Another thing when i backed it up and left it in reverse since the motor torques "off" the right side motor mount (where the ground is) it doesnt have a good ground and dies but when i left it in reverse on my steep ass driveway it pegged the temp gauge up past the red and the volts were like at 6-7....
Im checking the grounds later. I think that is the lucky winner though.
