Might be a dirty oxygen sensor.  Is this 323 an around town, short runs type
of use vehicle? If so take it for a hard run on a country road.
Dale P.........  aka Diddly

The first thing I would do is get some xylene carburettor/fuel injection
cleaner and flush out the throttle body and idle air valve.  You may
need to adjust base idle afterwards, since this will remove 9 years of gunk.

Don't clean off the black ring around the edge of the throttle butterfly
itself, since some of this is factory sealant.

Rather common and usually pretty easy to fix. Pick up a spray can of
throttle cleaner at parts store and follow the directions on the can. A
small amount of dirty or oily residue/gunk in the throttle body really
affects your idle. Also consider having your fuel injectors cleaned, but try
the throttle body cleaning first. Both operations will raise your gas
mileage.

!999 Mazda 323 with erratic, slowish idling. Drives quite normal everywhere
else. Sorry about off topic, figured there would not be too much of a
difference
                   John