Also check your grounds at the radiator and engine block,and starter to chassis.

The low coolant sensors on those earlier Detroits WILL shut down the whole show, even if your coolant is just a tiny bit low. Get a good Detroit mechanic to show you how to bypass that sensor.

have you chk'd for codes? the only 2 that will shut the engine down are low water and low oil pressure.it sounds as if there is a bad connection art a sensor or a faulty sensor...try this...unplg the coolant level sensor.take a paper clip and jump the plug on the end of the wire.tape the paper clip to the wire and secure the wire....that may be the problem. some people and companies have reprogrammed the truck not to shut down but go to idle.