Radar,
I always get my N idle settings close and then fine tune in D with the brake applied.
I am currently idling at 1050rpms in N and it dropped to 850rpms in D. The only thing that I can think of is that I am idling on the transition circuit at the 1050rpms and when it drops to 850rpms in D, it is then on the idle circuit.
I am going to drop my N idle to 975 and see what the O2 readings are. If this is correct, the N O2 readings should lean out some more.

Thanks for the reply.