Truck dies then restarts.....sometimes

[deezer5150]

A friend of mine has a 1995 PSD with about 250,000 miles on it. Lately it has been stalling with no warning. It does not always restart right away. I know, I know, you are going to say it is the CPS but it has been replaced multiple times. The glow plug relay has been replaced. The only thing I can think of is maybe the injector harness is having a problem and cutting off the fuel. I am at a loss and so is he. Any ideas you guys may have would be greatly appreciated. I'm going to post this in a couple of spots here so I get some coverage.

Regards