sounds like your wiper motor is going bad

Is your wiper control on the turn signal stalk?  Many Fords have trouble
with the Multi-Function Switch (wipers, signals, flashers) that act kinda
like what you are experiencing.  Does jiggling the switch make a difference?

PoD

 There is a set of contacts inside the wiper motor that are supposed
to open every time the wipers are at the bottom of their stroke, so
the arm stops in the parked position - when you pull the stalk for one
swipe, those contacts are supposed to keep the motor running till it
gets to the next park point.

 Sounds like those park contacts either have gone open electrically,
or the cam is worn so they aren't working mechanically.

 How that messes up the automatic three-swipe clean cycle is beyond
me, unless it's a separate electrical box counting two swipes by that
park switch and then releasing so the motor stops after the third.

 But since the park switch it's looking to for the count pulses is
broken, it sits there going "One - Okay where's two?  Still waiting
for pass two..."  (Myself, I'd just use a simple timer.)

      --<< Bruce >>--