I have an 06 6 S with reoccuring p0304 code (same problem, different cylinder). So far, they have reprogrammed the PCM twice, replaced the coli pack, and replaced the right side cat converter. Light still coming on and the had an engineer come look at it. He said that there is a compression leak right cylinder bank. My shops techs performed the compression tests twice, once with shop foreman looking over their shoulders and they found no leaks. Seems like they are guessing, but now the say they will replace the engine. Too little, too late. I am seeking Lemon Law for replacement.