No kidding?

 

Not to mention,IF his truck is a 99 with a v10, I feel fairly confident that there is only ONE temp sensor. So I don't what's going on with the "both of them" comment in another thread.

 

Ive had both of the problems the OP is describing.
The moisture in the passenger floor board turned out to be water getting in around the drain for the a/c. I sealed around it with silicon and havent had a problem sense. It would let water in if I used the a/c or even when it rained.
The gurgling in the coolant system is obviously air as you guys have been talking about. After I burped it several times I was stumped after I couldnt find an obvious leak. Turns out to be a leaking head gasket letting combustion gasses into the coolant system. Especially odd sense the lack of white smoke or any obvious signs.
Hope my story helps.

Hutch