Cylinder 6 not working
I'm new to this so please be patient with me.
I have a 2004 bmw x3 2.5L manual transmission. I was driving 75mph on highway when all of a sudden I lost total acceleration capacity. The vehicle sounded like it was running rough and was not able to fully accelerate unless dropping to 5th gear and running it at 4k rpms. I was 2.5 hours from home on the weekend with no good options. I stopped into Autozone and had them read the possible codes due to engine light being on ( which has been on for a while now and yes, ive payed to have fixed and yet a new code arises shortly after fixing).
Autozone read codes for misfire chamber 5 and bank 1 and 2 lean. I changed coil pack due to changing spark plugs few weeks before. Misfire code disappeared and continued driving. Drove nicely for about 45 min and then it repeated with losing full acceleration. Had codes read again and the only ones were the Bank 1 and 2. I made it home running 5th gear at 4k rpms. Now it runs like this all the time. I had a friend troubleshoot switching coil packs along with spark plugs. There was no change in engine idle after unplugging 6th coil pack. My friend said that its apparent to him that there seemed to be no activity with cylinder 6. The vehicle has 115k miles. Do you guys think that it's a high probability that the piston head is ruined. Or do you guys think it's most likely a fuel injector issue? The spark plug seemed to have quite a bit of oil on the end. My buddy also said that when taking the oil dipstick out it smelled of possible fuel. Has anyone had this issue and if so could you possibly give me some insight.
I'm new to this forum and forums in general so I apologize if this isn't kosher forum format.