Stalling with low fuel on hills

Hi, recently my vehicle died on me while climbing up a hill and the gas tank was right on the E line. I've been getting poor-gas mileage. The car would crank but not start on the hill. I had it towed to my garage and it started fine... A few days later I had the gas tank just below the E line but with more than enough gas to drive. I was drivin up a steep hill and the car acted as if it was gonna die, stalling but I made it up the hill and it was fine. So I figured that it's taking too much gas goin to the engine... What could be causing that? It's a 96 i30