Rough ride in my '01 Durango, help?

I've heard that these trucks are supposed to be pretty smooth, but apparently no one told mine that. It's a 2001 RWD SLT Plus with the 4.7 L. It's gotten progressively worse over the last 2 years I've owned the thing. I feel a lot of the road underneath the truck, and it takes speedbumps and potholes way rougher than I know it should. I know it probably needs new upper ball joints/control arms because I can wiggle the front driver's side tire a little when it's jacked up (the tire is mounted to the hub just fine), and the tires won't align perfectly, but I know that can't be the only issue.

Things I've replaced so far:

Rack and pinion

Inner and outer tie rods

Rear tires (now running 255/70R16 Valera H/T's, front tires are Cooper 255/65R16's that are about to get replaced with tires identical to the rears)

Lower control arms (both sides)

Front and rear shocks (running KYB Gas shocks)

Two front wheel hubs, one rear

What else could be going wrong? I can't tell if the rear leaf springs or the front coil springs are bad, how would I determine that? Could it possibly be the body bushings? I was at a loss after I replaced the shocks and there was no difference. Any help is appreciated.