I recently bought an optima that has a misfire at the #4 cylinder according to a code reader. I changed the spark plugs and coil pack, the car ran a little better, but still has a misfire. The misfire seems to go away when I'm driving around 40mph. It's not burning oil and the#4 plug looks like it is igniting. Do these engines have a idle air control valve and a map sensor? I couldn't find either.