1997 Plymouth Breeze

Engine Performance problem
1997 Plymouth Breeze Front Wheel Drive Automatic 112726 miles

The car I own is a 2.4 L 16 valve ply. Breeze. It's been making these 'sputtering' noises now for the past few months. On road trips, the vehicle would seem to lose power when climbing steep hills on the highway. At first, the sputtering noises were few, now it is constantly happening and is getting worse. When I wait at stop lights, the vehicles engine almost feels like it wants to stall because it feels like its lacking power to keep the engine going. And when it 'sputters' the fuel gauge hand dips down and comes backs up when it stops 'sputtering'. When waiting at the lights one time, I put the car in PARK and the sputtering stopped briefly, but then continued again but not as bad as when I have my foot on the brake. I have a few friends who think that there's water in the gas line. So I got some gas line anti-freeze. This didn't stop the 'sputtering' noise. Help.