Car stall, jerks and shuts off with A/C on even at full tank

Hi, my car (hatchback) developed a stalling, jerking and sudden stop problem after installation of a catalytic converter and for five months running. I have changed the spark plugs, ignition coil, fuel relay, used nine fuel pumps, changed slow jet, changed air collector, used two fuel pump casings, inner and 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 and P720. Please, what could be the possible element that reduces voltage to the pump thereby overheating it twenty to thirty minutes 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-12.48 volts and cranking-13.5 volts. When engine is idle, alternator-12.49 volts and cranking-13.77 volts. When engine is cranking, Inertia feed cable before switch-12.92 volts and after switch-12.84 volts. When engine is cranking, fuel pump-12.6 volts and during the stalling, jerking and sudden shut off situation, fuel pump-11.6 volts. The problem is intermittent. it occurs at odd times. Sometimes twenty times in a day, sometimes twice, three times, forty times, but it sure occurs. One cannot predict especially when the A/C is turned on. What are your thoughts on this please?