I've posted this problem before and got a bunch of great
suggestions on what to look for.  I've tried just about all of them now
and the problem remains, I can't think what could be left but the ECU:

        My '79 Westie starts up fine but as soon as the aux air
regulator shuts off, I'm running too rich, engine's running rough.  But
if I drive it within a few minutes it runs pretty much fine and normal,
the problem goes away.  On an average southern California 75 degree day,
it goes fine for about 20 minutes--less on a hot day--then the RMPs are
too high when I stop at a light, the idle is way too high, around
1300RPM and gets worse the hotter the engine, maybe 1400RPM at worst.

        Suggestions from list were to replace the hoses for a vacuum
leak, which I did, no change unfortunately.  The aux air regulator is
new, the head temp sensor I've replaced, these gave me more pickup for
sure and it runs better, but this problem remains.  The oxygen sensor is
new, replaced when I got it smoged, so it shouldn't be the problem.
BUT, the other day after it was warmed up and idling too high I
disconnected the oxygen sensor--viola, the idle went down to normal.

        Could this be anything but the ECU not properly dealing with the
signal from the oxygen sensor?  Everyone says don't suspect the ECU
until you've tried absolutely everything else, I can't guess what else
it could be.  HELP!