Intermittent stalling/failing to start

[GT915]

My stepson has an 05 Mustang GT with a number of bolt on mods. Intermittently, usually in the heat of the day, the car will fail to start or just quit altogether while driving. A shop that is local to him diagnosed it as a faulty fuel pump and replaced it. This lasted one day, and it's back to doing the same thing. When you turn the key on, normally you'd hear the fuel pump briefly prime, however we don't hear that when it's acting up. The car has 60k miles and all preventative maintenance has been taken care of including the replacement of the fuel filter. I'm wondering about the fuel pump driver module or the fuel rail pressure sensor. Any help or input is greatly appreciated.
Thanks

 

[Thump_rrr]

If he has a tuner he can set it up to read the fuel rail pressure sensor.
if the system is already pressurized then the pump will not start.
Check if the alternator is charging properly between 13.8-14.3V since these cars are sensitive to voltage.
Is this occurring randomly or after it rains?
Many 05-06 cars have had issues with water in the passenger footwell and the SJB Smart Junction Box in the passenger kick panel.