My 2007 mk5 Gti is Sputtering and misfiring at under load (normally 4th 5th 6th gear) have codes p300 and p0304 which would indicate Multiple misfires and Cylinder 4 misfire. So I'm guessing that means i need a coil pack for Cylinder 4. I'm toying with the idea of changing all 4 coil packs and spark plugs while I'm at it. Has anyone got any recommendations for the best coil pack and sparkplug combo???