The engine started to lose power, and the check engine light illuminated. The power drop was most noticable when accelerating from a stop. At times, randomly, the engine RPMs would dip down to 200-300 at idle and would almost stall. Upon further investigation, the engine has been excessively consuming oil. I brought the vehicle to a local mechanic shop to get a detailed diagnosis, they informed me the catalytic converter was clogged and constricting exhaust flow. The engine has developed a ticking/knock. The catalytic converter, and an O2 sensor was replaced with that visit. The ticking/knock persists.