what you've describe is typical of a tranny slipping. 80k miles on it? its possible its pooched. i'm guessing that perhaps on the longer road trip the tranny is heating up and thats why its slipping. and on shorter trips it doens't get to hot. could be a host of problems as to why its overheating. but slippage often happens from to much heat. heat kills auto tranny's. go do yourself a favor. pull your codes, see if it does anything.
to do this, go do the 'three' key trick to pull your codes. watch the 'OD' orange indicator light and count the blinks. this is how you can access any stored tranny codes. it will do a series of blinks and stop in between. so you will get, for example, 5 blinks, a pause then 5 blinks. if you get that, its code 55. that means no codes.
you might be lucky to get a code for a sensor or something. if you get 55, ummmm.....
92 YJ ~ locked/33" swampers
05' WK Hemi limited ~ wifey mobile
13' Chevy Cruze ~ boo
13' GMC Sierra ~ 2.5" lift 33" MTs.
RIP 95 ZJ ~ 33s built/longarmed/locked/awesome Feb 2014 ZJOTM winner