I had the car idling this evening, hard to start but did, ran it for 45 minutes in the drive, a couple of idle surges during that time. Then it quit. No warning, no sounds, no lope or chug, nothing. Just up and quit. Any ideas?
Thanks

 

Lots of ideas.

Fuel pump died. Could be the pump or the relay, or that Orange wire that the ECU earths for pump activity.

Inertia cut off switch had a hissy, they do that, and that will cut the fuel pump circuit 100%. A simple reset is usually all that is needed.

The CTS (Coolant Temp Sensor) in the LH thermo housing back section has lost contact with the ECU. With a good engine running, and simply unplugging that sensor will stop the V12 with conviction.

The ignition amp module has given up, OR, the infamous shielded wire that communicates a pulse to the ECU has died, very common.

Basically check and observe if the death is fuel related, or spark related.

The hard to start you mentioned has me thinking in many other areas, but the simple basics above is going to eliminate many of them anyway, and give us all a path of attack, with a minimum of $$ hopefully.