Need help diagnosing steering problem

[duke_togo]

Hi all,

While driving I occasionally experience some moderate shaking or shudder at the front end of the car that also noticeably manifests itself at the steering wheel (feels like someone is jerking the wheel from right to left, enough that I have to fight to keep the wheel straight).

It is intermittent, in other words, I have made recent trips without this happening at all. It is possibly happening more often at low speeds or right after braking, and this event appears to be increasing in frequency. I don't know much about diagnosing suspension or steering problems, so I wanted to pick the brains of the folks here.

Any help would be much appreciated.