It could do, there are a number of things it could be such as BOSCH plugs, these can cause the issue, as they can track chronically in zetecs, the leads can cause it, on the earlier zetecs leads ford used silicone grease inside the plug caps where it slid over the porcelain.
I suggest first take the plugs out and look at the porcelain part and see if it has any lightning type black streaks on it, as this is tracking, and is another thing to look at.
tabetha