I commented to Randy on what the POH recommended for idling to prevent fouling the plugs and Charles asked me where I found this -
It was in the section towards the back maybe titled Operations? within the first few pages. Don't' have it with me but hopefully this will get you close enough to find it. BTW this is an original POH not a Killough.
2 minutes in warm weather and 4 in cold.
I also taxi with the mixtures towards lean and once in a great while still have to lean to clean off a plug during run-up but not nearly as often as when we used massive plugs. The fine wires made a big difference.