Vehicle Shudder problems of the 2014 GMC Acadia

Twice in the past week I have had the same problem with the stability track sensor turning off while driving. When this happened the engine power decreased. When trying to get the vehicle off the road, it was like I had lost power steering because it was a fight to turn the wheel. Prior to this we have also noticed that when the vehicle shifts gears, quite often it is a very hard shift to the point it shakes the whole car and feels like it is stalling. Not sure if that is a transmission issue or something to do with the fuel injection.

Vehicle intermittently shifts to a high gear when starting to accelerate or starting from a stop without pressing the gas. As a result, the vehicle starts to shake and sputter, much like what would happen if trying to start from a stop in 4th gear with a manual transmission. Check engine light comes on, traction control and stabilitrak error appears on the display. Pressing the gas simply makes the vehicle jerk. After a few seconds, the error corrects itself and everything clears. Unable to duplicate at will. Took to the dealership today after this has happened around 5 times in the last month; however, no error codes we logged in the computer. Service department unable to do anything.