Hi Louis , I just had a look at some pics of the engine , so firstly engine hunting is normally associated with rich mixture ,poor idle as in rough is normally lean mixture ,however the system is using a throttle controlled by motor this is sending signal back to ecu and ecu is controlling the flow.
The inputs around idle are speed from crank and cam shaft air flow (some engines use air flow meter others use map and throttle position , in this case I suspect it uses air flow meter (not 100 %) so anyway . Here goes with my sugestions 1 . disconnect egr valve and see if it makes a difference .
2 . disconnect the air intake from pcv .do not block the engine side only the side that goes to the inlet manifold . and test car . 3 clean the throttle body and using VCDS or similar do adaption . 4 check for air leaks o inlet manifold (use small amount of petrol in spray bottle ,be very careful as it can cause explosion if reaches spark) 5 check values for cam timing and crank timing over rev range . I can go but suggest you try these first.
Al