I have a 2004 ranger, 4x4, 4.0L. Over the past month I've had stiff steering when the engine was cold. Just this Saturday evening it was about 10 outside and I had almost no power steering and I completely lost it around a near 180 deg. turn. I checked the fluid yesterday and I had plenty. Today I didn't have power steering at low rpm even after the engine was warm, but I did at higher rpm. I checked the fluid after about 50 miles of driving today and it was about a half inch below the minimum mark. There was power steering fluid on parts of the front of the engine. I bled the system after refilling, took it for a drive and it didn't fix anything and I didn't lose any fluid during the drive.

There wasn't any visible leaks or drips when I was bleeding the system, could it have overflowed somehow when I lost power steering Saturday night? Is it possible I just need a new pump and if so, is it hard to replace?

Thanks for the help in advance.