Steering box adjustment can make for a miraculous improvement.
It's not particularly easy to get at the adjustment screw.
The intake manifold is very much in the way.
The task is much easier if you grind down (the short end of) an L-wrench to improve clearance.
Just be careful not to overdo it, or the steering will bind coming off of center. Once it seems about right, try some high-speed turns to really test it out, like on an exit ramp. Can take a few tries to strike the right balance.
Best of luck.
1986 300E 5-Speed 240k mi.