2001 Subaru Forester car hesitates when putting on the gas

Hello,
My 2001 Suburu Forrester just started losing power when accerated and spits and sputters at a very low speed. It seem to run almost fine when using the cruise control going 55 miles an hour. I had filled my car with gas at the pump and the pump shut off after $13.00 worth of gas and my car was not completely filled up. As I checked the gauge inside my car. Went for about 20 miles and then it started to loose power and spit and sputter. What do you think this could be? Maybe some bad gas or do you think a fuel pump. It shakes the engine alittle and sounds like it puffs out the exhaust.