A common problem on the all applicable Mercedes is the Idler arm bushing failure. Over time they just wear out.
Also, pick up a steering dampner & a drag link. You should be able to buy an aftermarket draglink for around $50 & the dampner should run you no more than $35.
Oh yeah, the idler arm bushing replacement kit is pretty inexpensive as well. It is a project that you could handle in about 2 hours w/ a couple of 17mm wrenches & sockets !!