Hello and thank you for using just answer! I am here to help you with your problem, so feel free to ask questions until you are satisfied.
Which part of the plug was covered in oil, the white porcelain part or the electrode part that threads into the engine? Is the spark plug wire boot wet with oil?
the threaded part no oil on the boot diagnosed missfire still missing with new plugs and boots
Ok, if the electrode part of the plug has oil on it, you could have an internal engine problem such as a bad piston ring, valve guide seal, or valve guide. If the injector was bad or clogged, it would just prevent fuel from entering that cylinder. The plug would be clean.
You could do a compression test to determine the overall condition of the rings and valves. Make sure your getting good spark from the wire on that cylinder also. It is very common for the valve cover to leak oil into the spark plug wells on these cars, but that wouldn't cause oil to contaminate the electrode part of the plug.