2002 XG-350 enging surging problem- high standing idle

Hi to all - I have a 2002 XG350 that I purchased new. It now has about 131K on it and has been a relatively trouble free car to this point. A couple of months ago I noticed that the idle was quite high
while the car was stommed and in gear. It could probably get to 20 mph without using the accellerator pedal.
I brought the car to the dealer and was told that since there was no code/check engine light, that they couldn't diagnose the problem. I few weeks later there was a check enging light so I brought the car back in. They told me that it needed new ignitiuon coils, and a sensor that controlled the coils. While the car was in I got a call and was told that they also replaced the throttle position sensor. The car runs somewhat better but the problem of the high standing idle is still there, $600. later. Apparently the techs don't know how to adjust the idle.
I'm wondering if anyone has had a similar experience with a huyndai and maybe a solution.
Many thanks, Vic
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Thats odd. I,ve got a 2002 V6 Sonata that has a high idle. Thinks its the same engine bored/stroked out a bit for the XG350. Likewise the dealers seemed incapable of adjusting idling speed. If it was idling that high and smoothly I,d seriously doubt the coil pack was faulty. I,ve had them fail and totally the opposite. John
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The idle (and in this case, throttle) are computer controlled. No check engine lamp isn't the same as can't be diagnosed. No check engine lamp simply means that the computer's self-diagnostic capabilities haven't determined there's an actual problem.
There are several items for the technician to investigate: - Is the idle high due to computer request? If so, the various inputs to the ECM and throttle module (ETM) should be checked for proper values. Accelerator and throttle position sensors are strong potential candidates for this type of issue. - Is there an air leak bypassing the throttle plate? This would cause a high idle. - There could be a fault in the throttle body or the ETM, but both of these will typically set a trouble code pointing the technician in the correct direction.
Do you know what trouble codes were retrieved? Any chance the plugs were recently replaced or the intake plenum was pulled for some other reason?
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