Whenever I get to over 50 mph and hit the slightest bump in the road my jeep starts to shake uncontrollably.When I apply brakes and come to a stop it's ok.
shaking on 1999 Jeep Wrangler
You really need to check the steering suspension and tires. A shaking at 50 mph and over without touching the brakes would be tire imbalance, if it happens under braking only the brake rotors may be "out of true" and need to be surfaced or replaced, it could be due to worn suspension bushings, wheel bearing play or likely if it when you hit a bump the steering damper.
I had the same problem with my 2005 wrangler. It was the steering stabilizer ends. (both were gone).