where is the alt. voltage regulator located

Doubt it. Volt regulator is in the alternator and the battery would remain on while engine is running. I assume it starts back up right away. We need to check air fuel ratios, electrical like the iginition module, coil, etc...

First of all voltage regulator is in the alternator but sound like you have a issue with engine not running probperly. I would look at pulling trouble code first and go from their. Sound like vacuum leak or mass air flow problem...