1992 Ford Bronco Intermittent Starting Problem

My Bronco (70,000 miles on new engine) has recently encountered an intermittent starting problem. The truck will turn over, but not start. Initially, there was a fault code for a temperature sensor, which was out of range. It was replaced, and the vehicle started. Then, several days later, it wouldn't start. We replaced the plug wires and fuel filter. The vehicle then started. Then several days later, it wouldn't start. When I returned 48 hours later. It started. Last night, it wouldn't start. This afternoon, it would. It just cranks and cranks, but won't fire.

The only apparent common theme is that it was pouring rain on each occasion (actually, last night's failure was in a car wash).