It is adjustable AND controlled by the computer. There is an idle
control screw somewhere on the throttle body.
If you have fluctuating idle, you most likely have a vacuum leak
somewhere, so try to find this before you adjust anything. Fill up a
squirt bottle with water (others recommend using carb cleaner) and spray
a fine mist around the various parts of the intake system. When you get
a drop in idle speed, you have found the leak.
If this does not work, start pinching the various vacuum hoses until you
see a drop in RPM. If you do find a hose that allows you to drop the
RPM, follow it to look for leaks or faulty valves etc.
Another thread dealt with the same issue on a CRX. The original poster
in that thread found that his fast idle valve was leaking. It is a
thermo-wax valve that allows extra air in while the coolant is cold. His
was leaking air all the time.
If you do need to adjust anything, first get a shop manual as the
process is not completely straight forward. The best manual is the one
from http://www.helminc.com, but if this is the only work you are going
to do on the car the Haynes manual would probably suffice.
There is a stop screw on the throttle body (close to where the gas wire
is) that looks like the idle speed adjustment on carburetors. Do not
touch this screw, as it is factory set and is not used to regulate the
idle.
