My 1988 Jeep shakes violently at sporatic times. Sometimes when I brake and sometimes if I hit a bump. (And usually when I'm going atleast 50 mph)The shaking is SOOO bad that I have a hard time controlling the wheel until I slow down to almost 20 miles an hour. What is wrong with my baby?

Check out your shocks and springs. Check your shocks by pushing up and down on the bumper, then let go. If it bounces more than a couple of times, it's time for new shocks. Checkout all of your bushings also, especially on your anti-sway bar in the front and back. Next check to see if any of your spring mounts in the front and rear are broken. If you get bad vibrations when you corner, suspect belt separation on your tires. Inspect your brake pads in the front and shoes in the rear, make sure they have plenty of pad material left.

Search the forum for "death wobble". It can be caused by many things (both alone or in combination with others). You'll need to check them until you find the one(s) that are responsible for yours.

Have you done any work to it just prior to this starting?

Is it lifted?

i had that problem with my 88 jeep it was tie rod ends and a steering stablizer bar would only happen at highway speeds i used to shift it into 4wd and it would help till i fixed the problem

loose and worn out track bar was my problem, replaced it and haven't had any problems since.