Put new pump on steering turns each easy to left but is really hard to right
Might have air trapped in the lines. Hopefully the rack is o.k. Good Luck!
It does sound like a steering rack problem, most likely a stuck control valve.
No wait a minute a 94 won't have rack and pinion steering but a standard steering box. And last I checked you can still get a valve repair kit from your local parts store. If your into that. Otherwise replace the steering gear assembly.
Looking for a Used F-150 in your area?
CarGurus has 231,247 nationwide F-150 listings starting at $1,300.
Search Ford F-150 Questions
Ford F-150 Experts