Engine on 02 f150 cranks but won't start.

Our 02 f 150 4.2 died while driving on the highway, which seems to indicate a bad crankshaft position sensor. However, it had been running rough whenever it rained or had damp or cold weather and some explain this to be caused by water seeping in from the windshield and getting in to the area under the dash where the fuse box is located(driver's side). We have not worked on this truck yet, but was certainly due for some regular maintenance as well.