E83 X3 3.0d stumbling/miss/surge at idle, EGR related

[Derangedrover]

Gday gents,
Apologies if this has been covered before, have searched without success.

I have a new to me 2007 E83 X3 3.0d that is stumbling/surging/missing at idle.

If I remove the vacuum line from the egr valve the idle is smooth and at the correct rpm, it obviously causes a MIL for insufficient egr flow.

If I raise the rpm above idle, say 1000 rpm, the engine runs smoothly.

Other than the stumble at idle, the vehicle runs properly and no MIL.

I have removed the egr valve and cleaned it and applied vacuum to check operation, it moves smoothly and opens/closes as it should.

Can anyone shed some light on what components are involved in the egr circuit operation at cold idle?

Does the system use the airflow meter for feedback of egr flow?

My next step I think will be to remove the egr cooler and have a look at the bypass valve on it and see if it’s working properly or not.

Any pointers on what the problem could be, or relevant threads would be appreciated.

Does anyone know a source in Australia to have egr mapped out on this vehicle?

Thanks.
D