http://www.justanswer.com/nissan/3m7gs-1998-pathfinder-3-3-v6-crankshaft-sensor-top-bellhousing.html
It's at the 11;30 0'CLOCK position on the bell housing.
Hope that helps but I would try to pull some codes off of it to help narrow your search for the what might be a different issue.
Have you been ...