So I took my 2001 Cherokee sport kidding and when I was done a new clunking sound started.
every time I step on the breaks it sounds like my whole rear axel is about to fall off and it almost feels like the brakes are locking up. Any body in here dealt with this issue before?

crawl under and take a look.

Noggin pokin time

Yup. Agree wholeheartedly. Take a look before you kill someone with an out of control Jeep.
If you're not qualified, have it towed to a shop.

take a gander at the brake shoes orrr around the general rear end area. gotta look first.

I agree, you must do a visual inspection on the entire rear axle and brake components.

I had a similar issue when going to brake, a clunk from the rear of the vehicle would happen.

It ended up that the spring on the spreader bar in the brake assembly had broke from slowly rusting away and letting the brake shoes to float withing the drum...

Purchased a new hardware kit for both wheels and replaced all the hardware included in the kit. Haven't had a repeat of the problem since.

Hope this helps...

Just to add to the above, also inspect your shock mounts and rubber bushings, as well as your suspension and driveline components.

I'm just going to assume you still have stock drums in the rear. With that said, if your brake shoes inside the drums are out of adjustment or the hardware inside the drums is broken, this will cause the shoes to slap around inside the drum. But before you go digging there, do a visual/light hands on inspection to make sure your U-bolts, shock mounts or shackles are not broken or moving in any way. Good luck.