I drive a 1976 F-150 4X4 standard tranny truck. As I am driving down the road it turns off. I have replaced the ignition switch and key part. There is no real clue as what triggers this shut off because it does it randomly and at various running times.As I am going down the road with the truck off I simply turn the key and it restarts right away. Trying to figure out if there is a device that would open while it is suppose to be in the close position electrically. any one out there heard of this before. I have also changed my ground cable to the battery and cleaned the visible ground connections. Any ideas.

 

The brain box is a common problem.

 

+1
If its not it i would check all your wires