Q: Car says service stabilitrak and has a knocking noise.

The light could have come on for the brake fluid could be low and causing the system to see that the brakes are not safe. For the engine loosing power and making a knocking noise, there could be a misfire performing and shutting down one or more cylinders. Depending on the type of knocking noise and how much the engine looses power will determine if its just a fuel injector or the engines camshaft lobes are damaged. These engines are built very tight with hallow camshafts which can be damaged easy if the engine is under a lot of load and pressure (too much acceleration at a time). If you need further assistance with your engine making a noise, then seek out a professional, such as one from Your Mechanic, to help you.