UK Car Repair: Daewoo Lanos, daewoo lanos, vacuum line

Question
Hello William

Your category was the closest I came to regarding this question.
I have a '98 Daewoo Lanos, and have a very similar problem to a question you answered regarding this subject previously.
My idle meter sits on 3000rpm whenever the car is idle (traffic lights, warming engine, etc).  At the lights, I push and hold the break down and bring up the clutch till the needle plunges down to about 1000rpm or slightly lower if I'm feeling skillful.  At 3000rpm the engine is quite noisy, so I turn heads for all the wrong reasons. At first it was the auxilary air valve, it was cleaned first, and then replaced the second time, but on both occassions, it works as it should for 2 months and then gradually goes back to a high rev. You've mentioned a 'stepper motor', is that located at the front near the car's grill? Its certainly where the loud noise is coming from.  Can this motor be replaced? And how much would a typical stepper motor cost on average?
You've previously mentioned a vacuum line leakage, but the car isnt leaking.
Any advice will be greatly appreciated

San

Answer
To run at 3000 rpm it has a major throttle opening, you cannot continue to drive like this or you will burn out the clutch!  You have to trace the fault by blocking off the air entry points, start with the throttle body, remove the inlet tubing, with the engine running, seal off -with a rag or whatever- the throttle inlet, the car should stall as there is no air.  If it doesn't stall, listen to the sucking and trace where the air is entering ie, the Aux AV, or any other idle control unit