If it only stalls while you are slowing down (nearly to a stop) you could suspect the lock-up torque converter in the gearbox is sticking. First course of treatment would be to verify trans fluid is fresh and clean.

If it also stalls sometimes after you have already been stopped for some seconds, suspect something else because the lockup would have already disengaged and wouldn't go back in without added pressure. I wonder if there is some dirt in the fuel tank. This happened to me on an older Volvo. Random stalling and severe hesitation, much more frequent on a downgrade. It was so bad I replaced the tank and the fuel pickup line, which resulted in 100% cure.

Another possibility (assuming ignition is ok) is something in the primary wiring - main relay, ignition switch, etc.

Measuring fuel pressure and main voltage would be helpful - one or the other may be fluctuating a lot (they shouldn't much at all) but only occasionally reaching an extreme value at which time the engine dies.