Ok so I work on my jeep with a friend of mine. She presented me with a new problem we are unsure of. My onboard monitor just tells me perform service. I've got no lights on my dash to tell me what. I had the auto parts store run a check for me and it's a cylinder 6 misfire. Which I changed the spark plugs and coil less than 2 months ago. I'm going to check the plug again but need ideas in case it is fine.