My first thought would be to check if the linkage somehow got loose.
After that it usually gets internal and spendy.

Ford is notorious for bad automatic transmissions. It sounds like one of
your clutch paks burned out. I would check on a used trans at a junk yard.
You could also check with a local trans shop  on their price if you do the
removal and re-install. You can sometimes save a lot of money that way.
Pat