How can I diagnose worn tie-rods or idler arm bushing on my E500?

Hi,
I am having monster problems with my third child... :-(
Need help. Dealers here are borderline useless.
My 245/45/17 AVS DBs are feathered to the point that they make a horrible rumble at 5mph and high pitched whine at high speeds. Also ride rough.
However, when the car hits an irregularity in the road, its follows the irregularity, yanking the wheel almost. Car also feels unsettled on anything but a smooth minimally cambered surface. For example, on a country one lane road, which is appreciably cambered, it will sometimes drift to the centre, because of a mild road irregularity. Just had alignment done and everything is in spec.
Dealer also looked at idler arm and tie rods, etc. and felt nothing was wrong.
What is the best way for me to confirm that this is the case. What should I look for on tie rods, idler and wheel bearing? Could tires explain symptoms?
thanks in advance
farrukh