I test drove a 2010 Chevy Impala with 49,000 miles on it. The car steering seems tight, almost like a top that's wound too tight and about to spring. The car rocks at 60 mph on the highway -- the dealer said tires probably just need balanced. Kept the car overnight and "Service Stabilization Trak" appeared on the console. What does this mean? Does it directly relate to the steering at all?
Try pushing the esc button, you should be able to turn that system on and off. I wouldn't leave it off. If you cycle the key does it go off, I'm not saying turn off the key going down the highway, at idle. Any applicable trouble codes? You need to get it checked out.