p0300 on 1999 gmc yukon

the yukon has difficult accelerating especially in cold weather but recently would not accelerate at all till the point that the truck would turn off completely...the code the that came up was p0300 i have replaced catalytic converter, spark plugs, spark wires, distributor cap and rotor, and the camshaft position sensor with the replacement of these things i can drive it again at normal speeds but still hesitates on acceleration and must easy of the gas and than press down again to begin accelerating any advice would help