Wes, Good luck in your troubleshooting efforts, does your EX's V-10 have a non Ford oil filter on it? Hopefully it will turn out to be as simple as a bad filter resulting in a temporary blockage that is easily cleared. If things go worse and a replacement motor is the answer keep in mind that Ford changed head design in '02 to allow for more threads in the spark plug holes in the 2 valve heads. These 2 valve motors were used up untill the end of EXcursion production in '05. I have never heard of an updated V-10 head blowing a plug, the redesign seems to have eliminated that problem.
Good luck,
Tom
'05 V-10 EX