1996 Chevrolet Silverado C2500 w/6.5 liter Turbo Diesel, 4 speed Auto, with 226,000 miles.
At random intervals the engine cuts out while driving - although this occurs most often at around a half a tank of fuel. I have replaced fuel filter, in-line fuel pump and fuel cap. Often right before the engine cuts out, the "Service Engine" light comes on, but there are no error code (I have had this checked multiple times) or error code history in the on-board computer. Additionally, there have been a number of occasions when the engine hesitates once or twice about a mile before it cuts out. I have taken the truck to the Chevy dealer and they have no idea what the problem is - can you make some suggestions as to what to try next.