I assume the O-ring allowed contamination into the tank, eventually causing the pump motor to run VERY hot. When it ran long enough (on a long drive), I guess it got hot enough to boil the gas out of the reservoir, causing the stall until the fuel had time to cool down. That's the only explanation I can come up with that fits the symptoms. But it now has a
Bosch 67000 Fuel Delivery Module (the plastic reservoir with pump motor & valves inside). The assembly-line pumps in these trucks were Bosch, and I assume Bosch also makes the MotorCraft replacement pumps now. So I think this is as good a pump as can be had, at about 1/2 the price of the MotorCraft PFB1 (which includes the tank plate). The fuel lines are much cooler now, so I don't expect it to stall again. Before installing the assembly, I removed most of the water from the bottom of the tank.
IF THE IMAGE IS TOO SMALL, click it.
Oddly, there were a few scraps of plastic material in this tank, like I've seen in only 1 other...

While it was out, I also checked the level sender and found that the gauge responded exactly as it should. The float was dry inside.
UPDATE: The float sank a few weeks later.