1999 Pontiac Montana Vibration on Acceleration and de-accel

I have a 1999 Pontiac Montana with 122,000 miles my problem is two fold. First off upon mid range to heavy acceleration from a stand still the van seems like something in the front end is either jerking or not engaging correctly before it finally engages. My best guess is maybe the splines are failing either in the hub or cv joint or worst case the transmission. It does seem to do this much more easily after you brake from highway speed but that could have just been coincidental. If you hit the gas gently its fine and it does it at no other time except from a stop or very low speeds 5mph or so.
My other problem and possibly related is shaking when I hit the brakes. I had assumed it was warped rotors, having run into that before on other gm vehicles. I changed out the rotors and pads up front and checked the rear shoes which visually seemed ok. During my test drive the vibration diminished slightly but it still has a very noticeable shake. I spun all the wheels as well as shook the wheels checking for play, I did find one hub (passenger rear) with some play and will be replacing that as a precautionary measure. Thank you for your help.