I recently bought a 2006 cobalt ss sc. I can't pass emissions because of the mentioned problems. it threw 4 codes: p0304 cylinder 4 misfire, p2101 throttle position performance, p0130 bank 1 o2, bank 1 running rich. I'm convinced these are all caused by each other, a bad o2 or throttle position sensor could definitely throw everything off kilter. The fuel/air mixture is simply horrible, if the number 4 injector is being told to over spray fuel into the cylinder it could easily cause a misfire. But that's just a thought. I replaced the spark plugs, and switched coils 3 and 4 with each other, no change. I already have new coils on the way, mainly because that's just what I do when I buy a new car. I don't think new coils will help, but who knows. I'm gonna be replacing the o2 sensor tomorrow as well. Any help would be very much appreciated.