My 1998 Doge Dakota won't start when it rains.

You might want to inspect the distributor cap. Often times moisture gets under it and prevents spark from connecting. You may not even be able to see the crack that well. Remove it and look up inside it while holding it up to a bright light source. If you can see any light what so ever it needs replaced. Take your time looking, a pinhole leak will do it. Hope this helps.