I have had a cylinder 3 misfire for the past couple of weeks. I have replace the ignition coil, and wires since then. And it keeps coming back on after a day or two. the car runs rough during cold starts and at times while driving it will seem as if the engine is choking of tripping up. what else could it be. The rpms seem to be regular everytime. since i have had the coil and wires replaced recently it is running better. im in minnesota, could it be cold weather or what? please help