Replacement of the camshaft is a major job ( day and a half labor) and rarely fails on a Ford Explorer unless you had oil starvation problems. The camshaft position sensor is a key input needed by your vehicles computer to control ignition timing and fuel delivery. Cam sensor replacement is about .6 hours plus approx $50 to $60 for the part, then reset computer test drive and verify fix.
I know this was over a year ago that you answered this, but you mention it costs $50 to $60 for the cam sensor part. Any idea where one could purchase one? I can't seem to find one for sale ANYWHERE. Ford sells the full camshaft sensor and synchronizer for a cool $700. Not going to go there. I have a 93 Explorer.