well i know when the rotors are worped the brake pedal will pulsate but my peddle isnt pulsating my jeep is and it only between about 45mph on to 20mph

 

What are you asking exactly?? You post is pretty unclear...

 

the whole jeep pulsates under braking instead of the pedal

 

That can still be warped rotors, and that is where I'd start. It sounds like they may be really warped, and that would definitely make the whole vehicle shake. You should also feel it in the steering wheel. HTH!!

 

bad alignment will cause the front tires to get washboard effect
that you will feel when braking

 

sometimes uneven swaybar end links can cause the jeep to pull to one side or the other when braking. not sure if that helps at all.