just got back last night from wheelin on a mild fire trail up Big Bear Mountain in CA. Im in a stock 02 WJ, we went offroading with various breaks, lunch, etc. proly from 10am - 5pm. i was in 4 Low when ever we were on a fire trail. Towards the end of the day i noticed when in 4 Low only, it was shifting very hard into first and second and same for down shifting. and before it would shift up it was liek reving very high rpm like it didnt want to shift to teh next gear. it got noticibly worse as we went on but we were just about done jeeping when it was getting to the point where i was worrying alot. when i took it out of 4 Low at the end of the day after teh kicking started it gave the biggest kick. but i went right in to 4 Wheel all time it was fine. why could this be? anything im doing wrong? ANY HELP WOULD BE GREATLY APPRECIATED!!