Front end trouble on a 1995 Jeep Grande Cherokee All wheel drive 5.2L 8 Cyl.?

I've had the wheels balanced by 2 different places and my wheels still wobble when i make a left turn or hit a bump in the road, it stops the wobble when i hit the brakes, it's not a slight wobble the entire Jeep shakes like crazy even causing the rear wheels to lose grip from the road and "squeak" it's like the jeep is shaking side to side and i looked out my driver window and saw the front tire wobbling sideways, what could this be?