Just went through your symptoms again... totally missed that the temp. gauge is reading -80/85 degrees Celsius (-110/-121 F)... is your exterior temp. gauge damaged? As that would cause all kinds of issues... the throttle, maf and ambient temp. gauge work in tandem with one another to provide the correct fuel to air ratio. Obviously if it thinks air is -80c then it would presume that there is denser air entering the combustion chamber and therefore not opening the throttle fully.

Is your code scanner able to verify the faulty temp. sensor?

The sensor is located in the lower grill...
Location of Outside Air Temperature Sensor - Mercedes-Benz Forum

Unless it really is that cold where you are, in which case disregard.