Ministry of Agriculture and Fisheries - or Mass Air Flow, depending on context
In past times (previous Bosch LH and Motronic systems), the airflow meter (also known as AFM or AFS - airflow sensor) had a moving flap measured by a potentiometer. Moving parts are generally the first to fail, but the Bosch units are amazingly reliable.
Some engines, e.g. FIAT/Marelli IAW, do not have an AFM or MAF, but instead just measure the intake manifold vacuum (MAP = Manifold Absolute Pressure) and engine speed, and calculate the air flow from that.
The 156, like many other modern designs, has a MAF that depends on a hot element whose resistance changes according to the airflow over it. The sensing element remains at a temperature of 100 degrees C above the ambient temperature. The amount of current required to maintain that temperature is proportional to the airflow.
It sounds haphazard but is actually an accurate measurement technique that works at different altitudes and temperatures. Generally reliable; sometimes the element becomes contaminated by oil from an oiled-element air filter (I believe in using only paper element filters for engines that have a hot wire/hot film MAF).
As for EGR, that is one of those 'nuisance devices' that frequently gives trouble when the valve sticks, causing an erratic idle and possibly a fault light on the instrument panel. Reducing the combustion temperature does not help efficiency (power!) in any way and is not related to the Lambda sensor (which measures optimal combustion), but is done to lower combustion temperature to lower the emissions of nitrous oxides caused by the nitrogen in the air being oxidised. At the present moment, everyone seems to care only about CO2 emissions, so perhaps we should be improving power and efficiency instead... but who knows what is next in the environmental firing line... trees are dying in Sweden from all those nitrous oxides turning into acid rain, or have I got that wrong?