i have a 98 xj 4x4 automatic 4.0 and ive got a problem. i drive my jeep as a daily driver and it climbs a 4,000 foot elevation summit (interstate 15 fwy). I usually drop it into third to stay in pace with traffic, my RPM are roughly 2600 or sooo. Well today i droped it in two 3rd and it went up fine. As soon as i got off my offramp, to a complete stop. I gave it gas and it accelerated sluggishly as if i was barely toughting the gas. wtf? anyway i stoped at another light and was at idle, meanwhile im still in overdrive, it still does it until i put some foot on my pedal then it finally goes. Wtf??? I stopped and checked the fluid and yes it is dark but didnt smell burnt or shavings in it... well going home i was at a stop and it finally accelerated normal...wut could it be? did it heat up to where i lost viscosity in my transfluid?? time for a major service? it shifts and goes into overdrive fine...all ideas accepted. thanx