I have a 93 Ford Festiva. I have replaced the fuel filter so far, but still have no idea whats going on. It starts up and runs just fine, but when I drive it I am only able to put the gas pedal down a quarter of the way. Anything more than that it wants to cut out. When i let off the pedal a bit I feel the engine smooth out. But its just annoying only being able to take off at 1/4 throttle, and when going up hill i have to down shift because I cant give it enough gas to keep it up to speed with out it cutting out. Side notes: Like I said earlier the fuel filter has been changed. The owner before me removed the catalytic converter for some reason, and the exhaust has a huge leak back by the muffler...not sure if the lack of back pressure is causing the drop in power... codes that were read off it were 2 oxygen sensor codes and a "fuel system lean" code which I believe is making it smell like gas in the exhaust from the computer dumping more fuel, or it could be the lack of a catalytic converter... anyone have any ideas?