It rained quite a bit the past couple of days, and I notice sometimes afterwards my truck has strange behavior. So was wondering why the speedometer would not work at first when driving down the road but then it started to work again.

Also there was a slight feeling the truck was not running as powerful as normal when I had it in 4 th gear. but again things went back again to normal on the way back home from the store.

Anyone can guess what the possibilites are here?

Thanks.