Taking it to a shop that can read the adaptation data is key.
My initial pinion of the vibration would be that it is slipping when trying to engage that gear.
If you're a die hard DIY guy, then I would pull the pan and replace the filter. While in there, pull the valve body and clean off the two black magnets on top of the valve body (speed sensors). Higher mileage 722.6s get clutch pack material built up on those speed sensors. It can help a lot.
But as stated in the beginning of this, your adaptation data is key.