I have a `01 2500 Cummins. About 8 months ago there was a dead spot at about 35 mph, the tach and speedometer would fluctuate then continue to speed up. About 4 months ago the motor seemed to lack power, then slowly would not respond to any MASHING of the accelerator pedal at all. I would have to shut it off, wait for the light to go out then start it up and it would run fine. Then I took it in to dodge and they said the fuel pump in the tank and the injector pump were both bad, code P0216 or 18 I believe. Anyway, it was still less than 100,000 miles, so they changed it for free.
I am wondering if anyone else had experienced similar problems with engine lag. And if dodge/Cummins doesn't want to replace a known faulty item. By the way there aren't any new injector pumps out there, only rebuilt ones. Total cost if it was out of warranty - about $3500.