[Tervuren]

First step, lift and check for bearing play, second step inspect bushings, third step take wheels/tires to tire shop/machine and check balance of wheels/tires.

A likely culprit is one or both of your strut inserts is beyond function. If a strut insert is past its prime, any bump or imbalance is gonna throw quite the shimmy in the steering wheel.

I still had an issue after complete replacement of bushings, bearings, dampers(fronts were blown) and springs. Ended up taking my wheels/tires to a small town retired tire shop owner that had his own set of equipment at home. Problem went away completely.