Let me state that 90% or more of most severe drivability complaints (of this type) originate in the tires.
You have a top of the line car, do you have top of the line tires?
For those who don't know how to tell which are top of the line, use my method, which I use when I don't know about the subject: buy the most expensive. Which in the case of tires is Michelin. And just like the rest of the decision buy the best Michelin. You know how to tell.
And absolutely never listen to the tire salesman as he tries to sell you a cheaper tire that he makes twice as much on. Go to tirerack's site and find your base values and which models are available for your size. Then go locally and get your best price if need be. Get the best deal but buy the best product.
Bosch Master, ASE Master, L1
33 years MB technician