Few things to try. With engine running, unplug the connector on the ICV. Idle should increase. If it does, then valve is working and current is probably ok. This also proves that the OPR is ok since it supplies power to the ICU which in turn provides power to close the ICV. You might still want to remove the ICV and spray some carb cleaner in the valve end to get rid of the dirt buildup since it's possible that it may not be closing 100%. 4.8 ohms sounds about right. Mine is reading 5.0 ohms.

The Throttle Position Switch (TPS) is very easy to test. With engine running at idle speed, pull off the TPS 3-prong connector. Idle should increase. If it doesn,t, either the switch is defective or the ICU is bad. The TPS connector is just behind and to the right of the Cold Start Injector (CSI).

Cold and/or deteriorated solder joints are sometimes a problem with the ICU. If flexing the board didn't produce anything, it may be worthwhile to just go ahead and resolder all the joints just to be sure. If may take awhile but it beats having to buy a new one at around $300. I don't have a schematic of the ICU and don't know anyone that does. Maybe someone on this list has one and could make it available to the members.

Another thing to test. With engine at idle, turn on the AC to its MAX setting. Your idle speed should increase. If it does then the ICU is sensing this condition properly and at least this portion of the ICU is working. If the engine runs slower, then the ICU is not sensing the AC compressor is turning on. This indicates that the ICU is malfunctioning and needs attention. If the engine speed stays the same, then the ICU thinks that the A/C is ALWAYS ON and this could be the source of your high idle. Again this points to a problem with the ICU or even possibly the A/C Controller Unit (ACU) which generates this signal to the ICU.

Apart from the other items that you mentioned, I would like to add another as a potential problem source: The Cold Start Injector. If the CSI does not shut off completely, then it could be "dribbling" extra fuel into the intake manifold. Proper operation calls for the CSI to ONLY be energized when the engine is intially started in order to provide an extra burst of fuel for starting.

Testing the CSI:
After the car has started, unplug the connector to the CSI and make sure there is no voltage present on the pins. Even without any voltage present, it's possible that the CSI may not be closing fully and could allow extra fuel to enter the intake. The only way to prove this theory is to remove the CSI (held in place with two small hex head screws) and see how the engine runs. If you decide to try this you would need to fabricate a small metal cover plate to bolt in place of the CSI during testing. Place the CSI in a small leakproof container to observe while the engine is running. You might even be able to observe that the valve is leaking in this way.

Good luck and keep us posted on your developments.

T.C. Mann (aka TechMann)