My check engine light has been coming on and off for a month or so now. I just had my radiator replaced because it was leaking terribly and I wanted to have my car inspected while it was there. My mechanic told me the error was a misfire in valve one. He checked the plugs and the coils and seems to think I have big trouble with my engine, like corrosion or something. He's telling me that it could be up to $2000 to fix. I just bought it used one year ago and don't know what to do. It won't pass inspection with the check engine light on and the inspection is up in January. Any advice or ideas?