What's with my steering -- 1998 Passat

For a couple of weeks, by steering was bad–sounded loud, stiff. Fluid was low and foaming. Refilled it, still bad. Suddenly, noise stopped, foaming stopped. Fluid only a tiny bit low after three weeks. Now, at freeway speeds, can feel shuddering in the steering and the passenger seat feels like “Magic Fingers” has been installed–but only when I back off the accelerator.

Bad steering rack.