I think they have you fixed up... but just in case...
It sounds like hi-test (spark) problems. As they said, check your cap, rotor & wires are in good condition. Make sure all the leads are seated. (I've seen cars run fine w/ the spark plug wires not clipped on the spark plugs... until damp.) Then slide that cup *way* down on the spark plug. As mentioned, for extra seal, you can "glue" the wires onto the plugs with silicone. If you do this, glue them onto the coil and distributor cap, too.
Check the distributor. Lots of guys use a bead of silicone at the base of the distributor cap when seating it. Also buy some hose from an aquarium shop & put about 6" to a foot in place of the vent cap.
For really radical water crossings, like it sounds you are doing, you might consider an under-hood water deflector. The skid plates that go under the front bumper help deflect water down, but an occasional person goes more radical. These aren't water tight... they are just there to deflect most of the under-hood splashing.
Oh... and check all your other connectors, too. You already found one that was corroded, right?