Air Idle Control Motor , ICM or Air Bypass Valve regulates the air at idle through the throttle body. The car's computer controls the amount of air going into the engine by controlling the AICM, or other similar valve. Common problems for the air valves are deposits that cause the valve to stick or become plugged. An aftermarket repair or factory shop manual may list the test and maintenance procedures. Symptoms of a defective or plugged unit can include rough idle, or a car that wants to die at idle, but runs well above at normal driving speeds.
Alternators are a common failure item on cars.
To properly test an alternator, you need to measure the voltage and current out. Many auto parts stores have testers to do this if you take the alternator in, or may have equipment to test the alternator on the car. When idling, with accessories off, most cars will charge the battery from 13.2 to 15 volts. If the car has many accessories, you may need to rev up the engine a bit for the alternator to keep up with the load. If the output is high, it is probably the result of a bad regulator, or connection.