Hi Steve,

I also wanted to mention a couple of other little variables that could
influence your readings.

The rubber seal at the dipstick and consider adding a hose clamp where
the plastic oil filler neck slips over the metal oil filler tube- it's
junction is right in them middle of the alternator belt's path.  It
seems that these two items have a tendency to allow "false air" to enter
the system, that why they are sealed. The oil filler is just a friction
fit over a raised lip in the  steel pipe. Since they are source of
additional un-metered air their effect is a lean idle.

Also on the emissions side of things, crankcase oil can have gas in it
which also would be
a false reading point. I think this last point get's overlooked, but it
seems I read a considerable number factors that need to be address, but
basically baby the oil until your done testing.  Avoid lots of cold
starts without letting the engine oil recover from the rich mixture, the
testing instructions in your CO meter may address this too. An oil
change along the way could give your more accurate readings too.
Sincerely,

Mark Keller
91 Carat
Cowichan Bay, BC