Class C Handling Mod To Do First

I would start with heavy duty shocks. Bilstein made a huge difference on my 2012 E450.

make sure the tires are good, and if there are airbags installed you play with air setting to find best combo. I have a 12 aspect and it liked to wander, but it turns out the rear airbags and tire pressures had the most influence. 65psi F, 70-75 in rears, airbags at 55psi work for me as we dont load heavy.

Considered the sway bar upgrade, new shocks etc, until I found what worked. really costs nothing but fuel to figure out.

The first and cheapest thing to do is to have it weighed,front and rear and each corner if possible in traveling configuration,fully loaded as you would when heading out on a trip,then adjust tire pressure according to a Load and inflation table

Then you will have a great starting point to go on to new Bilstein shocks and proper alignment for your rig,then go on to sway bars and steering stabilizer.

Before doing anything, drive the used unit on the highway for many miles at 60-65 MPH with trucks passing you several times. Not a windy day. Check to see how it behaves on the road. It is possible that the unit may have had some improvements made all ready. I purchased a used 32' 2004 Winnebago. I have personally driven it over the highways over 6000 miles and it handles perfectly. I check the tire pressures before every trip and the tires are new.

Drove it about 600 miles home when I bought it last week. I've driven class C's before as well as trailers. It didn't feel horrible compared to past experiences, but I know it can be improved. I could feel the trucks, but not to the point of being nervous when I knew they were coming, and the steering just felt a bit sloppy, even on roads that appeared relatively level. I looked underneath during my pre-purchase inspection and noted that everything was stock. All tires and air bags were properly inflated before the ride home. Previous owner also drives and maintains trucks and kept the unit in immaculate operating condition. One of the reasons I bought it compared to other units I looked at that were a bit lower in price.

X 2 on tire pressure/weight, especially front axle. and then the air bags. The weight chart for the Michelins (front axle) recommends 60-65 psi. When the tires are set at 65, the handling is good. If the mechanic puts them up to 80psi (side wall max psi), it is extremely hard to control.
The rear axle tires are always set to 80psi, per chart according to my weight.
Having the air bags set to 70 does make a difference, (as opposed to 10psi after sitting for a couple of months). It is not as a dramatic improvement at the psi in the front tires.
Cost to try, virtually nothing.

Ken

In my case new shocks and front end alignment made a MAJOR difference on how the rig handled. I also suggest having the rig weighed and adjusting the tire pressure accordingly - it has helped make the ride more comfortable.

Ball joints don't last very long on E-series vans, especially the OEM ones. Buy the best ball joints that are available, which IMHO is Moog. I also recommend going to an "old time" alignment ONLY shop. I found a place that is 45 minutes away, but worth the drive !

Inner and outer tie rods last longer, so after ball joints, shocks.

If the steering damper is worn, replacing it will help. The old damper on my motorhome had apparently leaked enough oil that it had some air in it, which meant it had a certain amount of springiness before it started damping. A straight replacement damper made a noticeable difference in the steering feel. (I didn't put in a steering stabilizer, just a damper equivalent to the OEM one.)

Koni FSD shocks work very well but are not inexpensive. Installing shocks on the E series chassis is very easy in the rear and quite irksome in the front due to poor access. I found a flex head ratchet wrench and a lot of patience to be the key. There are some access holes that may or may not be useful from the passenger cabin under the floor mats; the exact location and shape of them varies with different model years, some being handier than others.

Alignment (including setting the caster to a relatively high value) probably has the potential to give the biggest bang for the buck. Weight and balance--especially having sufficient weight on the front axle--are also quite important.