Basically, the computer automatically maintains the idle speed for you. All you can do is adjust the throttle plate closed stop screw (which I believe you are assuming is an idle adjust screw). Once that is set you can go ahead and adjust the throttle position switch to get the "clicking" to occur at the correct throttle plate position - don't try to adjust the switch before adjusting the throttle stop. Also, the manual suggests that you perform the resistance/continuity measurements at the computer but I could never understand why you can't take those measurements right at the switch connection unless you suspect bad wiring between the switch and the computer. Make sure you are working with a clean throttle body and clean idle control valve.

Quoting the Chilton Manual:

Base Throttle Plate Stop Adjustment

Loosen the throttle locknut.
2. Loosen the adjustment screw until the throttle is com-
pletely closed.
3. Tighten the adjustment screw until it just touches the
linkarm, then turn a half à turn further.
4. Tighten the locknut without changing the adjusting screw
position.
5. It may be necessary to loosen the throttle switch before
setting the throttle.



Throttle Position Switch Adjustment

1. Open the throttle slightly and listen to the switch. There
should be a click when the shutter opens, if the adjustment is
correct.
2. Loosen the throttle switch mounting bolts.
3. Turn the switch slightly clockwise.
4. Turn the switch counter-clockwise until the switch clicks,
then tighten the mounting bolts.
5. Recheck the setting.
TESTING
1. Tum ignition switch to the OFF position.
2. Check the throttle switch by connecting an ohmmeter
between ground and pin 2 on the control unit connector. ohm-
meter should read O ohms (switch closed).-
3. Depress gas pedal slightly, resistance should increase to
2000-3000 ohms (switch opens).
Connect an ohmmeter between ground and pin 3 connection on the
control unit connector. Ohmmeter should read
infinity. (full load switch open).
5. Depress gas pedal all the way. Ohmmeter should read O
ohms.
6. If specifications are not as specified, check at throttle
switch to see if fault is in throttle switch or its leads. Check
ground connections at intake manifold.