So, my mom is out of town for a few days, and left me with the keys to her 2013 Volvo XC60 3.0 T6 with about 15,000 miles. While driving it tonight, it felt as if the engine was sputtering occasionally under acceleration. The car had its last service at 10,000 miles, and isn't due back until 20,000 miles. Does anyone have any idea as to what may be wrong with it?