I had the same problem that SEMO MIKE had . The transmission would act as if it was is neutral, engine would rave up, then go back into gear. I replaced everything, everybody knew they had the answer but their answer failed. A old time mechanic at Hudsonville transmission in Hudsonville, Michigan had the answer, Now get this ----- "the speedometer", 1992 to 1995 has a PSOM programmable speedometer odometer module built into the speedometer. It will short out and cause the transmission to do all sort of strange things.
Ford does not make a new replacement part the only option is a used speedometer replacement. Hope this helps out .