Car stalling, jerking and sudden death.

Hi, my 2005/2006 Ford focus hatchback car developed a stalling, jerking and sudden stop problem after installation of a catalytic converter and for 5months running. 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 codes PO230, P1100 & P720. Please, what could be the possible element that reduces voltage to the pump thereby overheating it 20-30minutes after working or when the A/C is turned on?

I took voltage readings for the battery, relay, inertia switch, alternator and fuel pump. When engine is idle, battery-12.48v & cranking-13.5v. When engine is idle, alternator-12.49v & cranking-13.77v. When engine is cranking, Inertia feed cable before switch-12.92v & after switch-12.84v. When engine is cranking, fuel pump-12.6v & during the stalling, jerking & sudden dead situation- fuel pump-11.6v. The problem is intermittent. it occurs at odd times. Sometimes 20times in a day, sometimes twice, 3times, 40times, but it sure occurs. One cannot predict especially when the A/C is turned on. What are your thoughts on this please?