We had this issue- shaking and engine light flashing at high rates of speed. Our 2009 RT was in the shop for over 8 weeks of the 8 months we owned it. The shaking issue took 3 weeks, 3 trips to the dealer and 2 rental cars to figure out. Ended up having to replace 2 engine cylinders, waterpump and various other parts. 2 months after that issue was resolved, we ended up having to replace the leaking transfer case. After getting the car back from that adventure, it never had the same amount of power but the dealer did not think there was a problem. This combined with various electrical issues (radio/navigation would not have power intermittently) and non-stop growling made the decision to trade this lemon an easy one. The dealer treated us fantastically and helped us out beyond what we could have ever expected (3 weeks of car rentals!)
Loved the features and size of this vehicle but could not keep it on the road reliably. If Dodge can get the reliability issues worked out, they have a winner. I went back to Jeep, still a Chrysler product but we've never had any issues with our Jeeps!