I have a 1994 Z/28 and everything seems right with my car. She runs BEAUTIFUL most of the time. Then it starts to rain. EVERY time I drive my car in the rain it misfires bad and I end up stumbling and sputtering home. Checked the wires for any arcing, the plugs are only 2 years old, and there is plenty of dielectric grease on the connections. Am I looking at replacing the Opti to solve this issue? Or is there something else I should be checking?

 

Your plugs are only two years old, but how many miles are on them?

 

You could still have "leaky" plug wires without seeing sparks. Rain (moisture in the air) will act as a conductor to help spark find ground where it otherwise might not.
How old are the plug wires? They may be ready for retirement.

 

could be failing plug/s, plug wire/s, coil wire, opti wire harness, opti.

 

The plugs have about 18000 miles on them as well as the wires. Change them both at the same time.

 

check plug wires to see if any are burnt or up against the exhaust. try some electrical grease on the plug wire ends, for sure the opti ends.