My 99 Galant es spurts/loses acceleration usually when accelerating. on 1999 Mitsubishi Galant

I have a code P0170. Tried replacing the MAS, CAM Sensor, And ignition failure sensor... to no avail. Its 4 cylinder 2.4 liter engine. fairly new engine block iin it with 15,000 miles on it with the valve cover gasket leaking very little