intake system cleaner is good for the plate.
the mass air flow test can vary because it could be ok while the Car is not running, and once driving the sensor resistance can change and the code would be stored for the fault. it's tested by using a scanner at key on engine off, then at idle then at high rpm and the out put should change when the gas pedal is pressed. But again. you can get good results and still have the code.
faulty catalytic converter doesn't cause this code.
don't replace the sensor yet. if you replaced the air filter and cleaned the filter housing real well, reset the code and re drive the code may not return. if it does then replace the sensor. Dirt or plugged air filter will cause this code to set.