What might make an 2000 impala sway some when hitting bumps in the road. (rear end) It is a 4 door SED

Replace rear shock absorbers.
Their function is to maintain contact between tires and floor. When they are worn the wheels spend too much time in the air without any traction.

A broken sway bar will also manifest itself while driving over an uneven or washboard-like road surface. A clanking or clunking sound will emanate from the front or rear suspension. Broken sway bars will emit knocking and scraping noises over potholes and dips, sometimes rhythmically. This happens when a sway bar bushing joint swings freely without support and strikes the chassis frame or control arm. Hope this helps.

could be cv joint but jack up wheels and move tire up down and left right up down if play check ball joints /anti-sway bar bushings--------if play left to right than check idler arms and steering system /and anti sway bar bushings

sounds like shocks

rear shockers gone replace both....as a pair.

Could one shock be bad? Causing a difference in bounce return rate? I would crawl under suspended car and check all suspension bolts. Are your bushings in good shape? If one is chewed up or missing then this would cause that misalignement. What kind of suspension do you have? Solid axle or independent susp? I don't know if your car is front or rear wheel drive. I'm guessing front wheel drive.

Could be your shocks are no good and need replaced or if you have rear springs check to make sure there are no broken leaves in the springs.

It's probably the rear sway bar links. If you can jack your car up and check right behind both rear wheels you will be abale to see the sway bar which is connected to short links about 5in long with ball joints.

If either of them are broken or not connected anymore it can cause some pretty loud noises when you ride on rough roads or hit bumps. They run about $35 per link so it's not a very expensive repair.

check shocks on back and sway bar for the engine wait until it dark and see if you have any sparks from wires and may need some new plugs i hope this will help you