This is a really old thread, but I wanted to update on my experience with this issue recently. Maybe this will help someone else.
I was having problems getting my truck to start and run well on humid mornings. Well I did a whole bunch of stuff tackling a whole bunch of other issues and the problem went mostly away for a bit, but the other rough running, not staying running issues got taken care of. I cleaned my old dizzy cap btw and that may have helped prolong my agony.
We went out of town in my wife's truck, and on Sunday while gone it basically drizzled all day. My truck was covered but basically in a car port. Monday I went to go to work, and the thing would not start at all. I went to look at it last night. I cleaned the dizzy cap, and noticed all sorts of corrosion at the connections. I cleaned it again and still no start. It was still plenty wet BTW. Bought a new dizzy cap only, at 9:05 this morning. I know I should have replaced a lot more, but I am not versed on timing issues, so I did not want to do more damange than good. Anyway, after 20 minutes of switching the caps, my truck fired in about .5 seconds with the first crank and ran great. Somewhat recently my truck has not started all that well. This may have solved that problem also.