01 325i misfire code p1347

What is your question?

It's misfiring on cylinder 3 iv swapped plugs around and coil packs Haven't check injectors out yet but threw some Lucus injection cleaner in.... But I noticed that there was a decent amount of oil on the plugs threads and cylinder 5 was pretty dirty I know that it could be the seal and iv heard about the pcv valve just not sure what the next step should be I'm trying to take the cheapest route.. Lose of compression idk....

How long has your 2001 BMW 325i had this problem?

A week