hi there, when air flow unplugged, ecu goes into limp home mode ,a back up if something dies whilst driving. it sounds as if your used mass air flow sensor is faulty , they are more fragile than they look, one knock and these early fine wire models are gone. i replaced many when i worked at a volvo dealership a few years ago. hope this helps, and good luck.
Have you checked the ignition module? More info such as eng size would be helpful to help you.
epc is short for electronic pedal control, the throttle is controlled by an electric motor and has two angle sensors in the throttle body. the pedal it self has two sensors as well, sometimes after a battery replacement or replacement of certain parts (ecm throttle body pedal controls) the control modules need to be reset or "relearned" to one another. the dealer or independent shop with correct softwear can do this, if problem persists possible bad throttle body pedal sensors or ecm (engine control module)
replace the fuel filter,if this does not help,replace the fuel pump.
Unplugging the mass airflow sensor may be ok to do just to get you back home,,but it is not wise to leave it unplugged,,because your engine control unit cant decide just how rich or lean to make the fuel mixture without it.
A smell of gasoline is usualy a sign of this.