Engine cuts out while driving

We need to start with checking for codes. If there is a code that can point us in a better direction then we need to chase that. If not, a diesel engine needs compression and fuel to keep running. So we need to suspect that we are losing fuel pressure to cause this to cut off. That means we need to check fuel pressure when this cuts off to see if it is dropping.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Also, did you change out the diesel fuel or is this the same fuel that was sitting in the tank from a few months ago? If so, it could have moisture in it or be stale at this point. I would suggest draining the tank, putting new fuel in, and a diesel fuel conditioner then see if it continues to stall.

Let me know and we can go from there. Thanks