Could be a bad sensor. I had mine go out, bought a new one, it went bad in less that 10,000 miles, the second one has lasted over 60,000, both bought from the Cummins parts counter. they are a bitc* to replace.

 

For anyone following this thread:

Turns out the half moon key from the Fuel inj. pump installed last year came out and the lock washer broke in half, the nut retightened ????? I haven't figured out the *how* of that yet... anyway, the pieces fell into the gears, chipped teeth on the vacuum pump and knarled up the slots on the tone wheel which is on the back side of the camshaft gear...

I fixed it. Yes, It was a b*tch, and i have pics if it will ever help anyone else, let me know..

Thanks for your input, everyone.