Heinz, thanks for that I have two of those joining at a T piece. The airbox is different to the Mondeo as is the hose to the throttle body. Hence the t piece I guess. Tomorrow I will disconnect them & put a circular pipe on the T piece to see if the fault goes.
The IACV arrived today & that has made the idle smoother but the underlying fault is still there.
Next step is to take off all the hoses & the filter box to recheck them for leaks if the test Sunday fails..
