Bravada Rainy Day Blues

I drive a ‘99 Bravada (180K miles)that I generally like a lot. Trouble is of late than on nearly every rainy day it will not start. My mechanic “Joe” was an Olds guy and says, “I get that a lot.” I have changed out distributors several times and have tried to seal up the cap with an electrical sealant with more coats than Elvis’ hair. Any ideas out there on a fix.

How old are the spark plug wires?

This I do not know, but I take this as a suggestion.

Spark plug wires, distributor cap, rotor. (if it has these parts.)