My Taurus shuts off while driving.

I have a 2006 ford taurus 3.5L v6 engine. A few months ago while driving it shut down and wouldn't start back up. We took it a Ford dealership and they replaced the fuel pump. One month later it did it again and they said faulty fuel pump and replaced it again. Fast forward a month and it did it again, this time I took it to another ford dealership and they said it was the onboard processor and replaced that Plus the battery. Now its been three more months and the Taurus had on 3 occasions shut down while driving but after sitting for a few moments it starts back up. The ford dealership said they can't find anything wrong with it and unless is totally breaks down and won't start at all there isn't anything they can do. We live is south carolina where is is very humid and my husband says he feels its water getting into the gas tank. I am not convinced. I am at my ropes end with this car. Unfortunately we can't afford to trade it in because we still owe a lot on the loan. Any ideas would help