Hard to start after fueling
 

1999 Maxima. Each time I fill my gas tank, I turn the car off. However, the car is hard to start afterwards. I out-smarted the car for a little and left car running while fueling. It worked for a little while. Lately when tanking up, I leave the car running, but when I unscrew the gas cap, the car stalls. After refueling the car is hard to start again. What gives?