Andrew
Have you read trough the posts at the top of this forum? Here is on that may answer some of your questions:
http://www.automotiveforums.com/vbul...d.php?t=672854
FYI....Windstars do not use dis caps. The wires come off of the coil.
Here is a clip from the above link.
SPARK PLUGS and Ignition:
The windstar factory spark plugs are rated for 100K miles.
The correct replacement spark plug is a double platinum plug......with platinum enhancement on BOTH the center electrode and the Ground tab.
This is because the windstar's ignition system uses a Positive spark on one side of the engine and a Negative spark on the other side. This causes the center electrode to wear faster on one side of the engine, and the ground electrode to wear faster on the other.
At this time, only Motorcraft and Autolite brands carry this type of spark plug.
I hope this may point you in the right direction.
Regards
Dan