02' 3500 6.5l turbo diesel *shuts off*

My van shuts off sometimes while i'm driving, when I go to restart it up it starts right up,somestimes. I've changed the glow plugs & same thing. I've changed the fuel filter several times. I've even changed the oil pressure sensor switch, someone told me that could cause the problem. That wasn't it. Now i'm at the point where i'm pissed! I also had a computer test & no codes showed up. any ideas
thanx,
Rod

Ive had the same problem and it was a injector drive module mounted on the side of the injector pump.