(My posts tend to be biography-sized..)

TL;DR: Are CATS equipped cars supposed to bounce like crazy sub 5km/h? (rhetorical question)

2002 S-Type R, CATS.
I changed:
- Rims: My own rims were getting a new paint job so the garage lend me a set of 19' with 245/40/19 all around, which is a bit too tall for the rear. No change
- Tires: Had 2 flats in the last year, the 'original' tires were down to about 3mm thread depth so I figured I'd throw on some 2nd hand tires until I'd replace them all, which I did when the rims were done, 2 weeks back.
- Shocks:
- Front shocks: about 1.5 years ago (they were FUBAR, previous owners, neglect and all)
- Rear shocks: about 6 months ago (Problem was already there, figured because of the 'bounce intensity' it couldn't have been something small, and seeing as the front shocks were FUBAR, they were suspect and according to the garage, pretty worn aswell)
- Tie rods: the steering was a little 'sloppy' aswell and the guy who aligned the wheels last assured me the passanger side tie rod was 'bent'
- Upper Control Arms: 2-3 years back, rubber on the ball joint was dry and cracked.
- Sway bar bushing: 3.5 years back to fix a rattle (didn't fix the rattle ofcourse, but I digress)
- Bushings and joints for days

Normal tire size (245/40/18 and 275/35/18)
Proper tire pressure (2.5bar front, 2.8bar back according to the FSM)
Wheels aligned and balanced, no aftermarket suspension components.

Symptoms (might be multiple problems):
- Nose diving when braking (And I hardly touch the brakes)
- Nose rising when accelerating (mind you, I drive like a grandpa)
- Sloppy steering in corners
- Lots of body roll in corners and roundabouts (again, I drive like a grand
- Slight steering shake at higher speeds, were talking cheap shaver level vibrations (both frequency and intensity), not warped discs level
- My god, the boucing below 5km/h.. As someone described on the internet somewhere else really well: "...Like a camel with a python stuck to it's *****"

So, whenever I'm snail-pacing in a traffic jam, the car bounces like I'm going over a branch every 10-15ft or so.
Everytime I tried showing someone, the problem was magically gone (thanks CATS..) and because I was fed up with the problem
I promised him he could keep the car if it wasn't bouncing this time around.
So I, after running my big mouth, tried to reproduce the symptoms so I could show my buddy.
Well I was pretty happy when I found out the problem happens if you JUST let go off the brake and have the car roll on it's own.
So as I was showing my buddy, we noticed the problem was gone the moment I even accelerated even in the slightest.

I remembered, reading somewhere, there was something about the CATS system and 5km/h so I hooked up my reader (iCarSoft LR II).
The module has a specific check for (iirc) 'Shocks firm: low vehicle speed' which stiffens the shocks when the vehicle is below 5km/h.
Unplugging any of the front shocks makes the problem worse and persist beyond 5km/h (CATS error, shocks Firm all the time, so fair enough)
So the module is still doing SOMETHING after 5km/h, and a broken connection to any of the shocks should throws a CATS error.

The only error in the module was a disconnected front right shock (which I caused myself)
I checked the 3 accelerometer readings, I'm not an expert on G-forces but the reading seemed pretty decent:
About 0.5 G lateral on a roundabout at -/+ 12mph and near 0.2 G on the front/rear sensors when driving on a super bumpy paved road.
(I was more interested in the sensors responding to input vs them being perfectly accurate)

The first thing that comes to mind (because of the bouncing), are worn shocks, but the indie told me they're in great shape.

He suggested I visit the dealer and see if they can get the 'firmness programmed' but I'm pretty sure there's no firmness programming on the ON/OFF shock type

I'm currently suspecting the springs as the car has been driven for atleast a full year on flat shocks and engine mounts. So all the car's weight was carried by the poor things.
I know sagging springs are extremely rare but the car is 20 years old and I've been over the rest of the suspension with the parts cannon already.

Anyone know of any low hanging fruits I'm clearly overlooking? I'd love to know.