2000 Ford Excursion

Hello, I have a 2000 ford Excursion with a 6.8L & 74,000 Miles. When ever it rains My entire electrical system begins shorting out. For example, Sometimes, while I am stopped & in park, the starter turns over like it's trying to start the truck. It doesn't do it while I am in park. Or the radio stops working as soon as I put into gear. It works in neutral. Finally, sometimes after a short run like 30 minutes or so & I park for a few minutes it won't start. I found that pushing the fuel inertia switch will get me going most of the time. After the truck " dries out", everything is fine again. No error codes on the computer either. Any ideas? I remember reading somewhere about water entering behind the firewall on the F250's but can't remember where.
thank you
October 22, 2007.

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