I have a grand cherokee that seems to hesitate when shifting between 1st and 2nd gear. If I am accelerating under normal driving when it gets to around 15 of 20 mph when it is shifting it hesitates on the shift. I can watch the tach go up and down and feel it jerking. once it gets past this shift it drives fine. If I floor the throtle it seems to do alright. No check engine light or anything like that is showing. Anyone have any ideas what could be causing this?