I changed my fluid too, using laser thermometer to get tranny temp up, pulled plug out until fluid sputtered out.  Also changed rear diff and transfer case too.  Still didn't fix the problem.  I also had someone look at it and said it was fine.  I didn't get a warm fuzzy though.  I'm thinking that "it's thinking", at least that's what I call it as a joke.  when you shift it does a few things, one of them being changing the orientation of the side view mirror's as well as turning the rear view camera off and turning on the GPS view.  My thoughts are that it's going through this bunch of tasks and it hesitates before it actually starts to go forward, at this time you are applying more gas in the anticipation of it moving so it jumps forward.  I would love to hear if there are anyone else that have experienced this as well and their thoughts on it too, it drove me slightly crazing trying to figure out wth was happening.