2000 Chevy Van have spark sometimes and mostly no spark whe

Went through rain parked van afterward it would not start till next day. Started ran fine then same thing till next day. Got her home realized sometimes she has spark and sometimes she does not. Replaced module, coil cap and rotor only difference is she will start more often but could be cause I am doing diagnostics and I don t let her get hot. But still spark sometimes and not other times the latter being the rule. Battery is good, van cranks, and runs perfect when on and does not shut off on me. Problem is when I shut her down no start only every so often if I try enough times or mess around between coil and cap I feel that if I can get the sparks regular then she will start regular.