2002 Saturn L200 poor acceleration

My 2002 Saturn has been having trouble accelerating up hills. The RPMs increase and the engine gets louder, but the car continues at the same speed until the road flattens out. I have used "Gum-out" and this has not helped. You can almost see the fuel gauge go down, I drove approx 50 miles and it took a 1/4 tank of gas. Would really appreciate your expertise. I thought it may be the catalytic converter, but not sure.