Is there quite a bit of blue smoke upon startup when its running rough, and if so does it end when the engine smooths out? If that's the case then pull your #2 spark plug and see if the spark plug tube is filled with oil. There is an oil passage less than .5" from the #2 plug tube. If it is filled with oil, you'll need to replace your spark plug tube seals. Alternately, if #2 is dry then its your valve guides that are shot.