Not sure if the original member here ever solved their problem BUT as of last night, my 2004 Vibe GT was running great and out of nowhere it started misfiring! Decent temperatures 45-50'f, slightly damp as it was raining earlier, did NOT drive through any deep puddles, conservative driving too. Anyways it threw the p0304 code (cylinder 4 misfire detected). After reading on here through several posts, I figured it may be the coil pack OR oil trapped in the spark plug well. I do have a pretty good oil leak coming from the valve cover (I'm pretty sure anyways) and possibly oil got into the well as a result of this? We'll see. Going to get it into my shop in the next day or two and get it fixed. Will follow up with my findings later