I have a 93 325is with 213k on the clock. It recently started misfiring on cylinder 4. It only seems to do it when it's warm and when it's running under 2k RPM (that I can notice). I just changed the spark plugs today and I plan on getting a new coil pack for the cylinder soon, but I can still hear the electrode firing in the cylinder. I'm also replacing the valve cover gasket soon as that is also leaking. Any other suggestions?