Car switching off and wont idle

Check your mass air flow sensor. With a scanner that can read live data, look at mass air flow sensor reading. Should read grams per second. So if your engine is a 2.0L you should see something close to 2g/s on your reading. Tap sensor and see if readings change too much or drop out close to 0. If it does replace the Mass Air Flow sensor.

Forgot to mention, that reading is while vehicle idles and no loads on.

Just to add, is the check engine light on?

No engine light on. the car has normal readings just not holding idle and keeps switching off when slowing down. mechanic is saying head gasket then others says manifold intake gasket others saying o2 sensor, but what you are saying makes sense as it does sound like it is sucking in air and revs are under 1000 rpm's so it struggles to keep idling.

Just to add, when mechanic plugged in machine he got an error p0108 map sensor.

Check your map sensor signal voltage. At sea level you should see around 1 volt.