Toyota Repair: What is ruining the ignition switch?, camshaft position sensor, toyota 4runner

Question
I have a 2000 Toyota 4Runner that was converted into a HMMWV type vehicle. When I took it to get inspected, the windshield wipers fuse blew. We started looking for shorts and after wiggling wires for a while, the windshield wipers fuse stopped blowing. Everything seemed to be fine for awhile. Then one day after a rainstorm, the truck would stall when shifted. Once it dried out this problem seemed to go away. Weeks later, after another rainstorm, the windshield wipers fuse blew and the stall when shifting problem started again. This time the ignition switch started acting up, running the starter even after the truck was running and sometimes trying to start the truck without the keys in the ignition. We assumed the ignition switch was bad and replaced it. All the problems seemed to resolve for awhile. Then, they returned. We assumed the ignition switch was bad again and replaced it again. Again all the problems seemed to resolve for awhile. Now, they have returned again. What is ruining the ignition switch? Should we be looking for a bad ground? A shorted wire or componet? Why is this happening usually when there is moisture? We tried replacing the starter relay with no success. The check engine light came on the last time we had the problem, so we hooked up to the OBDII test interface. It threw a code about the Camshaft Position Sensor. We checked the ground for the sensor and found it was also related to the windshield wipers and ignition switch. It was loose, so we cleaned it up and tightened it. We also sealed up the fuse box with some rubber matting. Well, whatever the issue, it is not resolved. It rained last night and the truck started up fine this morning and shifted into drive just fine. It continued to rain on and off all day today and when I went to go home tonight, the truck started up fine, but stalled when I shifted into drive. Then when I started it up again, the starter continued running after it was already started and it stalled again when shifted into gear...then last night the truck tried starting itself without the keys in it, so I unhooked the battery. Not sure where to go from here. Thanks in advance for any help you may be able to provide.  

Answer
There is a serious electrical problem, possibly some wiring that making contact either to one another or to ground which would take a lot of testing with a volt ohm meter and some wiring diagrams, the problem is not the switch, this is not something I can help with, I can only tell you what I think it is and that is the wiring harness.
The first thing to do is to visually check all wiring and insulation for burned or broken wires and repair as necessary.