I think you've been getting some conflicting & confusing info
on your idle problem because nobody who's trying to help you
has the same car - '84 5KS 2.2. I have an '87 5KS 2.2 which
has the CIS-E FI system. I bet your 84 has either that, or
the earlier CIS FI. Either way, I think the most likely thing is
a malfunctioning idle stabilization system. I don't know how CIS
does this, but the CIS-E uses a cylindrical valve which allows a
controlled amount of air to bypass the mechanical throttle. The
valve has an electrical connector on the end, the voltage (from
the computer) at this connector controls the amount of air passed
by the valve, and therefore the idle speed. If it's all working
properly, messing with the idle screw will not change the idle rpm,
as the valve will automatically compensate.
Assuming your car has the idle stabilizer valve, find it, and try to
figure out if it's working right or not. Here are some things to try:
With engine running:
tap on the valve & see if rpm's change (sometimes they stick
pull the connector off, see if anything changes (proves valve is
Look at voltages on the connector from computer - is it trying to
control the idle? Actually i seem to remember a varable duty cycle
square-wave signal is used as the control, rather than an analog
d.c. voltage, so this may be hard to do without a 'scope.
This kind of messing around should tell you if the valve is broken,
or is ok but is not receiving correct control signals.
I apologize if none of this is relevant to your car.