[wiswind]

Take some extra time to label the spark plug wires!
It is SUPER easy to get them crossed when more than one is off at a time.

Also, take extra time to avoid bumping any of the many vaccum lines loose....and carefully inspect to make sure that they are all connected.

These 2 hints can save you hours of frustration and troubleshooting.

If you decide to replace your spark plugs.....do NOT use the multiprong Bosch plugs that they push at the part stores......they don't seem to be the best in the windstar application.
The correct spark plug would be a double platinumn plug.....sold under the Motorcraft and Autolite brand names.
These have platinumn enhancement on BOTH the center electrode and ground tab.

Another hint.....while in there....double check that the linkage to the IMRC is present. On the newer windstars (1999 and newer) the nylon clips are known to come off.....one possilbe cause for pinging...and other issues.
The IMRC linkage is in the lower intake manifold....passenger side.....there is a shaft that passes through the air passeges for the front bank of cylinders....and another shaft for the rear bank.....connected to a motor that drives both shafts.