Subaru Other

I have a 2000 Subaru Outback with 114343 thous and a 2.5 liter. My problem is two fold. My car lags sometimes when I accelerate almost as though I were about to flood it. I thought about changing the spark plugs and was disappointed to read in the manual that basically " it might be too hard for you so just go to the dealer". It was if they knew me. After I finally actualy found one of the spark plug caps and drew it out there was a good amount of oil in there. I replaced the cap and the car started and is running as before, but was that normal for all that oil to be in there? And what can I do to help with the lagging as I drive?
August 11, 2007.

Could be a valve cover leaking double check bcuz if its not we have a serious problem

Aug 11, 2007.