I forgot to mention that the theft light on the instrument cluster was indeed flashing rapidly when all this initially started happening. I noticed it after reconnecting the battery and getting it to restart. So I am not totally convinced that good old PATS is not somehow involved here.

Truck has an alarm system. Factory install? Don't know. It's got a red blinking push button indicator to the left of the steering wheel. And when the alarm was activating, it would sound the stock horn, not a separate siren. Additionally, whenever I would need to disconnect the negative battery cable, the horn would beep upon reconnecting. It does not do that anymore. Clue?

So what are the facts that I definitely know:

The battery is new within the last year.

The truck has always started just fine for me, up until just recently.

When the engine kill happens, on all but one instance, it always happens within 3 seconds or less after the engine starts, with the vehicle in park.

The other instance was within 2 minutes with the vehicle stopped, brakes applied, and transmission in drive, sitting at a stoplight.

The engine kill is random in nature. It might go for a few days and be fine and then it starts acting up again.

When the engine quits, it does so just like you turned off the key. No stumbling, stuttering etc.

After the engine quits a clicking sound is heard under the dash. Attempts to restart after this result in nothing. And there is no power to anything, headlights, radio, 12v plugs, dome light.

Disconnecting the battery negative and reconnecting it, usually, but not always, allows power back to the cab and a successful restart.

Once the vehicle is running beyond 3 seconds, it runs and drives normally, save for the one instance at the stop light where it died within 2 minutes of start up.

The engine kill can happen whether the engine is completely cold after sitting all night, or after sitting just a few minutes and trying a restart. It makes no difference.

Fuel filter was replaced not long after purchasing the truck.

This is my only vehicle. So it would be really nice to have it running reliably again soon.

That is all I have for now.