I have a 2000 5.9l dodge durango. Sometimes when I'm driving down a road like the interstate for more than 40min at 60-70mph my rpms will jump up about 500 and go right back down kind of sporadically. Also my dodge started to jump up to 1-1.5k rpms while idling or in park when the truck is warming up. It usally idles around 600 rpms.

Is my tranny going? Or is it something else? Should I get it checked out or is it something cold weather could cause?

 

start by changing the TPS it is notorious for causing these jumps while cruising, especially when the cruise control is active

 

+1 on the TPS.