Did it store any diagnostic trouble codes (DTCs)?
Only on rough roads? That's most likely a loose or corroded connection somewhere.
Where do you go for your vehicle's maintenance? Can they also do diagnostics?
Does fuel level affect the stalling one way or the other?

Focus on the Ignition Control Module (ICM). There may be a connection issue between the coil packs and the ICM or the ICM may be failing, due to the vibration. Consider replacement.

I would also disconnect the negative battery cable and clean the main ECM ground. The failure of the ECM on my Honda happened after I had been driving on a very rough road in Texas. Vibration likely played a part.

If the problem persists, check the ignition switch for wear. Ensure spark plugs are not loose and go over electrical connections to the ignition system. Disconnect the negative battery cable, before doing any of this work.