I am not familure with the spark distribution for the V10. Does it use the traditional cap and rotor or is it computer controlled
I ask because maybe the fix is in the distirbution. If there is a cap and rotor, try checking those and maybe replacing just to see if it fixes it.
I was looking and found this web page about the Triton series in general
Consumer complaints about Ford Engines - Spark Plug Defect
You might be interested in some of the comments on this page.
One more thought. Autozone has a reference library online and I found this on ignition systems there; Ignition System