Sudden voltage drop to the fuel pump

[Chuddy]

Hi, My 2005/2006 Ford focus hatchback car developed a stalling, jerking and sudden stop problem for 3months now. I have changed the spark plugs, ignition coil, fuel relay, used 9fuel pumps, changed slow jet, changed air collector, used 2 fuel
pump casings, inner & outer fuel filters and changed the brain box all to no avail. I have also washed my fuel tank from clogs. Diagnosis displayed error code PO230 and P0720. Please, what could be the possible element that reduces voltage to the pump thereby damaging it 20 minutes after installation/change. Does the alternator have any direct link to the fuel pump?. Thanks