Many Vans that become dwelled in, are older with tired springs and worn shocks barely adequate for an empty van, and then, they are overloaded.
The difference in handling of such a van compared to one whose ride height and spring rate is similar to when new, compensating for the dweller's load, is VAST.
My rear leaf springs were very tired. Ideally I would have gotten new leafs, but instead, I added firestone ride rite airbag helper springs. The reduction in leaning around corners was the most obvious effect, and big rigs at highway speeds could not push me all over the road as easily.
KYB gas a just shocks on all 4 corners further increased handling confidence, but are a pretty stiff shock compared to say a monroe reflex.
In 2012 I rebuilt front suspension and used thicker coil springs. With the correct PSI in rear airbags for the load I carry, good brakes, and properly inflated tires, even this top heavy van handles impressively.
Regarding brakes, many rear drum brakes do not self adjust properly, and then the front disc brakes then perform more work than they would have to otherwise, and stopping distances increase greatly. It seems the long life brake pads have no bite. Most scared I have even been behind wheel was with both feet on brake pedal, 220 LBs pressing everything on it, and the van only barely stopped in time with my long life brake pads from Napa. This emergency stop, would have not been an issue in another vehicle, it was only the emergency stop that revealed how anemic my brakes were, causing me to take action.
I now have Hawk HPS performance pads, bedded in properly to Brembo rotors, and can lock up the front brakes easily. I tend to rotate my tires more often than necessary, and When I do so, I pull off the rear drums, expand the shoes by the star adjuster until I cannot get the drums back over them, then contract them just enough until I can, then another click or 2 to make sure they do not drag. There are other methods.
Driving around with anemic brakes is dangerous, and not just to yourself.
Spend money and effort here first.
If your parking brake goes to the floor, it is very possible your rear drums are not self adjusting properly.
Improvements in my van from this point would be a RedHead steering gear, as the Apsco reman'd gear I installed might not leak, but is horribly worn, and cannot be adjusted tighter, safely. I replaced the Pot steering coupler with a flaming river U joint for a huge improvement in steering slop, now it is all within the crappy quality reman steering gear itself.
