[davekc]

If a dealer looked at it, then one would be under the assumption they did a voltage test at the fuel pump.
If that is ok.....what is it showing on the ECM activity report?
That should catch any irregularities at the injectors.
Flashing the ECM wouldn't hurt, but may still not correct the problem if it is a speed/rpm sensor that is having a issue.
I would have to think that between all of these, it should tell you something.
Maybe even a slight leak with the after cooler will cause your symptoms.
Not sure on a cummins, but I have also heard that a temp sensor at the intake will cause this as well. It is sending the wrong temp to the ECM and giving it a false reading.