Starting problem

2000 diamante , great running car, starting problems when it gets damp. Wont start for 2 to 3 days . Tried to tow it to be diagnosed 3 times, and every time we get to repair station it starts. Can’t diagnose unless not starting. We cant tell if its fuel or spark problem. Any suggestions ?, very frustrating.

This is an electrical problem and someone has to check for wires with cracked insulation.