WHILE STUCK IN STOP AND GO TRAFFIC I TOOK MY FOOT OF THE BRAKE AND MY CAR STALLED. NO WARNING WAS GIVEN AND MY POWER STEERING TURNED OFF. I WAS ABLE TO TURN MY CAR BACK ON AND PULL TO THE SIDE OF THE ROAD. AFTER WAITING FOR A FEW MINUTES TO MAKE SURE IT WOULDN'T HAPPEN AGAIN I PULLED BACK ONTO THE FREEWAY. WITHIN A FEW FEET WHEN TAKING MY FOOT OFF THE BRAKE MY CAR STALLED AGAIN. I WAS REAR ENDED AND HAD TO PULL OVER TO THE SIDE OF THE ROAD AGAIN. THE TEMPERATURE WAS 101 AT THE TIME. WHEN SPEAKING TO NISSAN I WAS TOLD TO USE PREMIUM GAS AND ONLY FILL UP HALF A TANK AND WAS SENT AWAY WITHOUT THEM LOOKING AT MY CAR.