I would look carefully at the spark plug cables, that is an item that is very susceptable to dampness problems. They seem a bit new and kind of low mileage for your problem, but it still seems the most likely suspect. I don't think the distributor cap would be the problem as if water got in, it wouldn't evaporate out that quickly. Also, you might want to wipe off everything that is high voltage related, dirt and water makes an excellent conductor. Mike W.