Hi all, here's my scenario. Where would you start troubleshooting this?

1999, K3500.
The engine was rebuilt within the last 5 years. It has less than 20k since rebuild.

I drove 1/2 mile and parked for 3 hours. All is well.
I then drove home when the engine died. I was able to coast to the curb.
The engine never got up to temp so I'm thinking it’s not the PMD. Although the PMD is at least 15 years old.
I tried starting the engine but it did not start.
I tried starting again with success.
I put it in gear and started moving the truck. The engine died again.
I turned the key to start it again but it wouldn't start.
I turned the key a 2nd time with success.
I put it in gear, moving the truck 10 feet and the engine died again.

I'm stumped. Where to start troubleshooting.

The engine was rebuilt within the last 5 years. It has less than 20k since rebuild.

Lift pump? Replaced during engine rebuild. I can hear it click when I turn the key to warm the glo plugs.

I am replacing it today just to be sure.

PMD? I ordered a new PMD from Leroy Diesel and will replace it this week.

Some folks have suggested the ignition switch?
I will check the fuses today too.

Thank you everyone.