I have a 1989 F150 XLT Lariat with a 5.0 EFI engine. It started sputtering and then died as if it were a fuel filter. So far I have changed the filter, in tank fuel pump, high-pressure fuel pump,

Check the EGR riser pipe to be sure it's not cracked or clogged with carbon. Try Lucas Deep Clean.

if you know for a fact that the battery only reads 10.8, that would be the problem. your pump will not work properly under 12 volts. This is why it has its own circuit and doesn't rely soley on the ECU fuse relay. of course there is a fuse that controls the fuel relay as well. Keep an eye on those. Secondly, if there is one on that truck, check out the over looked FPDM. The driver module is usually hiding on top of the spare tire in the back. Deteriorates so easily over time and therefore it cannot communicate with the rest of gasoline system. So, no gas for you to the block. good luck