89 F150 4x4 - Hard Turning

Posted this thread on E-series yesterday by mistake. Truck is very difficult to turn sharply (shudders and jumps) at slow speeds. Truck acts as it is in 4 wheel drive but that does not appear to be the problem. Was told a possibilty was front axle u joints but those checked out okay (see below). Also wheel bearings seem to be fine (wheels are tight when trying to move vertically). When I was checking for possible failure of the u joints by manually turning the front wheels, power steering fluid squirted out of the cap (not on correctly). Could there be air in the system or has the pump failed. I have been noticing a hissing sound the last couple of weeks when turning the wheel at slow speeds, and then all of a sudden this happened. Any help would be appreciated! :banghead: