Check your coil pack for cracks and try spraying it with a water repellent such as WD-40.
Cap and rotor plugs and wires may be worn
No, but bad spark plugs or plug wires sure can.
tune up. check wires and plugs possible worn connection and arching off where it should not be.
Chek out the ignition coils, the wires and the spark plugs..
Plugs, wires, coil, distributor, injector, internal engine....
Yes, absolutely!See "Related Questions" below for much more about changing Windstar plugs and wires
How about the plug wires? If plug wires don't fix it I'd bet it's the injectors.
Wet/damp/faulty ignition wires, contaminated fuel (water), worn out spark plugs.
The distributor cap of an ignition system is one possible cause of many for misfires. Other possible sources to investigate are the distributors cap and gears. The flow chart of diagnosing misfires also include the coil, capacitor (if applicable), ignition wires and the spark plugs.
If you are certain the wires are connected to the proper spot on the coil pack then it is likely the coil pack is bad. This is a sonewhat common problem not only on these engines but on very many across many manufacturers.
Sounds to me like you need to replace the spark plugs, spark plug wires and rotor. If the condition still persists, replace the distributor cap.
Start by replacing all the spark plugs. If that does not solve the problem then replace the spark plug wires.