A lot of people replace their MAF because it maybe causing a problem. You can check if your MAF is faulty by simply running the car with the MAF disconnected (note - this will store a fault code). If the problem goes away when doing this, then your MAF is faulty and should be replaced. If not, then it's most likely something else.

 

Not true. Disconnecting the MAF will just put the car into limp mode, which will then only use sensors that are necessary for the engine to run like the crank sensor, and disregard the info from a few other sensors that are just there for fine tuning and emission control etc.

 

It's been my experience that a focus with a serious MAF fault will run better in 'limp home mode' than with the MAF attatched, and this could save a needless MAF replacement.