lots of oversteer and wind sway
 

I've looked for a post by Stevebfl about this topic that I remembered about but I coudn't find it. The problem is my '94 E320 wagon with 230,000 miles on it is starting to drift and float a little on the highway and has become more sensitive to wind. Also, the most noticable thing is much more oversteer in corners. The tires pressures are all about 35 psi and the car still has the original shocks. It feels like I'm correcting the steering from the back of the car. Where should I start since almost all of the parts are still original believe it or not.

first job is jack front wheels of ground and check for excess play in the wheel bearings and trackrod ends

The front end is as tight as it was when I bought the car with 66,000 miles on it. Thanks though. The problem I describe gets worse with a load in the car too.

does it have gas rear suspention?? if yes then look there

gas/hydrolic that is, could also be weak/broken rear springs

rear control arms, links, and bushings is what most people have described to be the reason for a 'floating' effect on highways. but that's only from the rear end that you'll feel the car float effect. if it's in the front as well then i would suggest you have the alignment checked.
good luck.

Links on rear are common and the most common is the thrust link. This is the lowest one and is at a 45 degree angle to the chassis.
Front end most common is the idler arm bushings..
Both short $$ and two of the first places to look/check..

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1A70KFNW8&year=1994&make=MB&model=E-320-004&category=L&part=Thrust+Arm

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1A70KFNW8&year=1995&make=MB&model=E-320-004&category=M&part=Idler+Arm+Repair+Kit

While not related to your problem, 35 psi in your tires is not the recommended tire pressure. Way to high.

Some people like to run tire pressures a little higher than recommended to increase tire longevity, but 35 psi is probably the maximum pressure allowed in the tire you are running.

Hi Paul, I know it is a little high but I am constantly driving with a load (two very healthy little girls). I'll try lower them a little and see if I like it. I also understand that the quoted tire pressure on the gas filler door is the minimum recommended pressure (right?). Question: Does high tire pressure affect tire perfomance in the rain or is it tread depth and pattern dependent only?

I think Arthur sparked a dormant synapse in my brain :p with the thrust link comment as I have found the elusive post by Stevebfl about this issue from November 2000. Hey, I'm not complaining about my car, with 230,000 miles it is still amazingly solid, very reliable and looks nice too, brilliant silver with the all leather black interior and new rims with the SLK blue center wheel caps.

The tire pressures on your gas filler door recommend two tire pressures: one for minimum load, and one for maximum load. I don't know how many pounds constitute a minimum load or a maximum load.

Nevertheless, the "minimum load" tire rating is 27 psi front, 27 psi rear.

The "maximum load" tire rating is 28 psi front, 33 psi rear.

I'm willing to bet that your two little girls probably fall comfortably in the minimum load category.

I generally am in the car by myself with no passengers, but I still run 28 and 33 psi.

I clipped an article from an automotive trade magazine that discussed tire pressures.

It speaks to the confusion regarding what is the proper tire pressure - what is stamped on the sidewall of the tires, or what the decal inside of the door or on the 'B' pillar says. Following is an excerpt:

"The Rubber Manufacturers Association told federal regulators that those pressures stamped on the sidewalls of tires should be eliminated. They are, simply, the maximum inflation pressure for the tire but are a "source of misinformation and confusion" for consumers, the group said.

Donald Shea, RMA president, went on to explain that "the current listing (on the sidewall) of the maximum pressure on tires is not the recommended normal inflation pressure."

Rather, you should use the tire pressure recommendations found on your vehicle's decal - also in the owner's manual for your vehicle- to properly inflate your tires. These figures are determined specifically for your vehicle and take into account your vehicle's weight, handling characteristics, etc."