Similar thing on my '97. The key sometimes works perfectly and sometimes doesn't turn at all in the driver's door. It always works in the passenger door, and the power locks work, so worst case I unlock the passenger door, hit the switch and walk back around. Since it works perfectly sometimes and not at all at other times I don't think mine is stuck. It seems more like the key isn't lining up with stuff at times. But maybe I'll try some WD-40. It can't hurt.

 

I have the same issue in the passenger door on my 2000 F250. I have power locks that work normally and the key works great on the driver's door. I have no idea how it works but there is an anti-theft feature where if you hit the lock button twice on the fob the door locks no longer work with the key until they are unlocked with the fob again. I figured my lock issue was related to that.

Anyone familiar with this system?

 

Someone might be able to help you in the 1999+ Super Duty section. Super Duty & Heavy Duty - Ford Truck Enthusiasts Forums

This section is for 1987-1997 trucks

 

I would definatly ask the superduty guys. When I had my super duty they helped out a lot so they probably will find an answer to your question in no time.
Trav

 

Hey Nothing Special, when it acts up have you tried turning the key over? I've had a lock cylinder that was sensitive to which side of the key. Even though both sides looked the same, there obviously was some difference...

 

That's a good thought. I don't think I've tried that, but I will the next time it happens. I almost never lock the truck so it might take a long time before I figure it out and I might not report back here.

(sorry for the delay this time, I was away from internet access for the last week)