2007 997 was running rough. The Durametric said misfire cylinder one. Checked the forums and saw most likely culprit was either bad spark plug, bad ignition coil, or both. Oreilly’s had the Bosch spark plug and a coul that was labeled Import Direct. For the sake of convenience I bought the plug and coil from them. The coil was actually the newer version Beru (oem) with the longer bolts. Much easier job than I ever imagined. There are good tutorials on YouTube. Engine runs great and I cleared the codes. No check engine light and codes haven’t returned.