91 200q fuel filter etc

[John Cooper <Jacques.noir@worldnet.att.net>]

Ed, I live in the Denver area, and routinely travel over 11,000 passes
to get to Ouray and back every month or so.  My '91 200tq Avant has
never suffered from any changes in idle speed or perceived mixture
changes owing to preciptous altitude changes.  These cars are
self-adjusting as to both mixture and ignition advance because of the
maps built into the EPROM in the ECU.   If you have recently replaced
your Lambda sensor (Ox sensor) you should be comforted by the fact that
your car will always be in correct tune for any altitude you will
encounter on your trip.  Even if you do find a way to change the idle
speed by, say, changing the throttle idle stop, the ICV will
automatically compensate.
There is no accessible idle mixture adjustment.
Coop