Carbon can build up on an idle air-control valve, making it stick. When it sticks, it cannot control the idle of the car--it might make the car idle at a very high RPM or, in most cases, make the car stall at a low RPM. Cleaning an idle air-control valve can keep you from buying a new part, but only certain idle air-control valves can be cleaned. The idle air-control valve must have a spring-operated valve for cleaning to make it work.
Locate the idle air valve on the engine--it's near the intake on the side of the engine.
Remove the electrical plug on the back of the idle air control valve with a screwdriver. Do not break the plastic tang holding the wiring harness to the sensor--that's what keeps the wiring harness from vibrating off the sensor.
Remove the screws or bolts holding the idle air-control valve on the block.
Hold the valve pointed downward, and spray the pointed end of the valve with carburettor cleaner, and wipe it clean. (Don't allow the carburettor cleaner to drip into the housing.) Repeat until all the carbon is removed.
Replace the idle air-control valve and attach the wiring harness.
Start the car to make sure it idles properly, and test-drive the car to make sure the engine does not shut off when you are turning a corner or coming to a stop, especially with the air-conditioning running. If it does, you will need to replace the idle air-control valve.
Do not get carburettor cleaner on the electrical connections; try to get as little as possible in the body of the valve.