Hi, I own a 2009 smart car. It has 85000 miles and driven to work round trip 84 miles a day. My avg. speed driven is 70 miles per hour. I'm experiencing a rough idle and occasionally throw a P0303 code. I've reconditioned the fuel injectors, replaced #3 coil, performed compression test changed plugs, checked all electrical connection. I have yet to solve my problem. Can anyone help me?