There seem to be two questions in one here.
1. Why won't the truck run well on all cylinders?
2. How could the truck actually run on only one cylinder?
The first question is the standard test/troubleshoot/tune item that pops up weekly.
The second question is unique...could it really continue to run on one cylinder only. If that answer is 'yes', it might narrow the search for clues to question #1.
I like Carryall Jerry's 'auto ignition' theory..a diesel in drag!
Stuart
