98 9400 w/n-14

Are you saying it actually quits running or just stops pulling at 1600rpm? Depends how hot it is outside, and what temperature thermostats you are running, your oil temp probably isn't out of range. Stop leak and general corrosion will clog the oil cooler over time and slow down the cooling effect.

 

Get it to Cummins so they can plug in their laptop to find the problems, should only be about $120. Then, if is something simple, you can fix it yourself.

 

The only time my N-14 shut down is when my coolant sensor went bad.
Check that

 

If you get it to Cummins, they can tell you. Then you can go buy the parts & do the repair.

 

On my Volvo, it is a small black plastic stick on the bottom of my coolant tank-where I fill for radiator. It;s the size of a 3 inch long pencil-black.