I have had my Mazda 6s 3.0 for 9 months (currently at 80k), and recently it started shuddering in idle. Also, the acceleration has slight jerks in it and there is not as much power. FINALLY after about a week of this - a misfire code for 2nd cylinder came up. I replaced that ONE ignition coil and there was a good improvement of the smoothness in acceleration. It still idles kinda rough and im wondering if I should go ahead and replace ALL of the coils/sparkplugs. What else should I check? Also If i turn the cabin air on defrost (air from outside coming in) it smells a little like gas. Im not having any mpg issues but I find it strange - might have anything to do with all of this? And where does this fit in with the pre-cats? Called a couple muffler shops who "dont do that" when asked about cleaning or servicing a precat. They just want to replace them all together for 2000$. I have liked my mazda but this is starting to scare me a bit. please help.