My 06 with only 69000 miles did a strange thing while towing the camper. Going up hill in od it down shifted to 3rd and when it went to lock up it felt like it slammed in and out 3 times before I lifted the throttle. It then locked and seemed fine as I babyed it home the last couple miles. When I went to back in the driveway I had to put it in 4 low cause it wouldn't push the camper up the hill. Fluid level was ok not burnt but now have a slight drop from converter inspection cover. Later in the day I had to tow another trailer that weighs about the same along the same route and everything worked flawlessly other than the drip. The truck is stock and I have changed fluid and filter and adjusted the bands yearly. Any ideas?