what would make my steering get stiff changed steer box and steering shuck but on 2005 Ford F-250 Super Duty

after pulling my horse trailer the steering would get hard but not all the time changed the steerig box and steering shuck but still does it but not all the time hard to steer but then lets go then it is easy again sometimes hard to keep on the road started messing up after pulling the horse trailer

by in Rachel, WV on May 07, 2013
1 answer
ANSWER by on May 07, 2013
Pump is failing.