[Beardyboy]

My car is booked in on 8th Oct to look at a lumpy idling issue that seems to persist.

On a cold start, when the revs are up to 1500, there is an intermitten  lumpy vibration felt through the pedals and drivers seat. the rev counter doesn't flutter.

When on the move the car performs fine...although im convinced its a little more sluggish.

When stationery, the idling becomes lumpy....sometimes very noticeable. Again, the rev counter doesn't flutter. When I monitor the revs using the auto link tool, I can see theres fluctuate between 630rpm and 690rpm.

Any thoughts on what might be causing this?

Ive recently has the fuel injectors changed to resolve the warm start issue.

[Dazzler]

Damn! Sorry to hear you are having these issues. Being a rarely reported issue you would almost suspect the replacement injectors (or their installation.) 

[mickd]

I offer no help whatsoever,  and can only say that I would never have thought to hear
 - i30 and lumpy idle , together.