Doncha just hate these 'intermittent' faults. Never shows up in the dealers.
I doubt yours is a cylinder not firing David as I am sure that would have shown up somewhere in the dealers; maybe not though if it didn't do it. Of course, if it was the ICV playing up then that is an open-loop system and doen't throw a fault code.
I have to say that the idle on my K12 was spot on (the 11,000 rpm sticking throttles nonsense aside
) but the idle on the K13 is somewhat less than perfect. It tends to wander up and down around 1,100 rpm even from a cold start and also when hot. A blip will clear its throat and it is OK for a while but it isn't as precise as the K12 was.
Interestingly, the K12 had a couple of new ICV's during and after the throttles saga so perhaps that was why it was so spot-on.
I have a spare 'new' one so I could try popping that in the 13 and see what happens to the idle.
Is this something lurking deep inside and waiting to catch us all out?