Gap or no gap, a plug covered in oil suggests you've detonated in that cylinder and have broken the piston and or a valve. A cylinder not firing correctly will cause you to smell rich from the exhaust. There's your smell. The noises echoing through the exhaust is another clue something upstream is not right. A $50 borescope and 5 min of your time is better than $100+/hr for ford to dick you around some more. I only mention it because you were distressed about money in your last post. Good luck man.