Hello I've got an 02 x-type n lately I've been having horrible mileage so I decided to do a tune up.. Went and tried to change the plugs n noticed standing oil in my plug holes and my plugs were saturated.. Could that have been the source of my problem or something worse has happened?

 

X-Cited, odds are, you have the seals that go between the valve cover and the plug holes leaking, leading to the standing oil. Yes, the oil can lead to issues depending on how far up the plug it was. In short, if the oil was able to make a streak between the metal tip of the plug to the block of the engine, then that would provide a current path, shunting part of the spark away from the cylinder.