My 2006 Kia Optima...when ever I go to gas station and add gas it will sputter and die.

A stuck open evap purge valve. Its located back by the fore wall . It will have an in and out vacuum line and a 2 wires on it. Try pinching off the vacuum line that heads back to the tank. When getting gas. It starts fine with the line pinched off un plug the elect connector and see if there is vacuum with car running on the side of the line that goes to the tank. If there is replace. The evap purge valve . Let me know how this works out .