It could be a problem with the fuel pickup in the tank, or it could be an electrical problem with any number of systems that only shows up intermittently.
Is it affected by the fuel level?
This is likely to need hands-on troubleshooting, use of diagnostic tools, fuel pressure gauge, etc.
For example, a diagnostic tester can do a 'snapshot', allowing the technician to review the data at the time the vehicle stalls.
It is a very unusual problem. It could be any number of things; you are likely to get any number of wild guesses. For example, your vehicle does not have ignition wires. This one isn't a good one for diagnosis over the internet.
Does the car not have warranty?
Was the car recently purchased? Were any accessories removed from the car recently?