I was always impressed with the incline holding ability of my TJ (230 000km with AT overhauled at 35 000km because of wave spring), but lately it seems to roll. Gear changes are good, fluid is good, level is correct and a cooler is fitted. Could this be a symptom of a pump that is not working well/ on its way out?? Idling (on dash rev counter) is about 500/600 and steady, but this is lower than it used to be. Does lower idling speed dramatically affect holding ability? If I increase idling to 700RPM (assuming this is possible) is she likely to regain holding ability. Even on a slight incline she rolls and sometimes it is worse than other times. I can use handbrake on inclines so this is not the issue. I am concerned that the transmission is on its way out.

Next time you're checking, gently push the accelerator to bring the revs up to 700-800 and see if it holds better. If so, then there's your problem. Idle speed issues are usually sorted with a good clean out of your throttle body, there's a couple of threads on this and MadMagna has created a tutorial on his old site here (http://www.madmagna.com/).