Touring edition van has 205K miles on the clock. Recently threw codes P0300 and P0302. No history on previous tuneup so new NGK plugs and new Delphi coil packs. Cleared codes and back on the road. When replacing spark plugs, noticed copious amount of oil in one of the spark plug tubes; noticed this tube and a couple others were higher than the rest. Codes came back within a couple hundred miles so took her apart again to reseal those spark plug tubes. Swapped spark plug from cylinder two with cylinder six and coil pack from cylinder two with cylinder four. Back together and on the road. Still have a rough idle in gear and P0300 has returned as "pending". What else should I be looking at? Van cruises great!