Truck will shut off at running temp and not start below threshold code whatwrong

I have checked the connection with a multimeter and all the wires seem to be good and the connectors read correctly I have checked the pedal.....this has been going on for 2 years and had no codes until I changed the fuel pump......the previous owner had all kind of DVD players a viper alarm remote start put in that does not work the alarm went off by itself one night i had to yank the alarm horn out to stop it im concerned it maybe bad electric work....also on a hard right turn it would bogg down and almost stall