ED30 misfire on idle - Cyl. 3

[PTR12]

So my ED.30 is misfiring for a while now. It only happens only on idle, warm or cold, on cylinder 3, with 1 or 2 misfires on cylinder 1 and 4.None of the misfires are bad enough to trigger CEL and idle is stable, around 750-800RPM. It simply feels like the car is shaking a bit from one second to another, nothing violent.
The car is stock. It pulls well and does not misfire at all when driving.
It has even compression on all 4 cylinders. So far, plugs and coils were changed and the intake valves have been carbon cleaned. Took it to various mechanics and they said it's fine... Any idea of what should be chased?

[GreigC]

It’s most likely the injector or injectors… Classic issue on our cars unfortunately. Whilst removing the injectors you may as well do the valve nut blast cleaning as they get covered in carbon. You can send your injectors away for flow testing and they will report on repair/rebuild or replacing. Another symptom of injectors is shaky cold startup….

[PTR12]

Can injectors be tested in any way without taking them off? At least to have an idea of how bad are they

[GreigC]

You will need to remove them and have them flow tested to know.

[pudding]

Can injectors be tested in any way without taking them off? At least to have an idea of how bad are they

Not necessary, the injector has had it.

The only long term fix is 4 x brand new ones from VW.  Removing the intake is a pain in the arse so its not worth just putting one in.  The other 3 will go the same way.