hey i just got a tune-up on my car.. new rotor, cap, wires, plugs, and fuel filter.. and this is the gas milage that im recieving... the only things i havent changed yet was the pcv valve and someone mentioned o2 sensors, but if both of those are bad will is cause 10 mpg.. i mean my car is a 4cyl.. someone help me out becuase this is really hurting my wallet! thanks