Sometimes my transmission hard shifts from 1st to 2nd. When it starts, I have to park it for an hour or so,then it shifts like normal. I've had the truck for about 2 years now and it's got over 250000 miles on it. It's done this to me 4 times now. Any ideas to why or what it is? First time it did this was after towing my pop up camper up to a camp site 50 miles from my home.

 

If you haven't done it in a while, it might be worth servicing the transmission. Drop the pan and swap in a new filter.