Maybe it's not the fuel system at all. The recent work there might be drawing too much attention. Failing fuel systems usually give a clue since the engine dies due to low pressure. There's usually sputtering and low power before shut-off. Your clues seem electrical .
Since you have lots of time while waiting for things to cool down you should be able to get out a meter and/or some noid lights or test lights and check the things that need power and ground. Check for power at the coil, power at the injectors, injector activation when the engine is spinning, and spark. Narrow the possibilities down.
If everything checks out then you'll have to consider the dreaded but not unheard of ECU failure. I've mentioned before in long past posts that I had a 78 ECU die on me while I was giving it a test run. Just died instantly, restarted, after a few seconds, let me drive another mile, then died again. I put the old 76 ECU back in and everything was fine. After that adventure I always carried a spare ECU behind the seat.
The other common failure point is the ignition module. But you'll get pointed that way if you have no spark.