Citroen AX idle problems

Hello to everybody. I own a AX 1.4 92model year with KDY A2.2 Bosch engine. The last days when i start the engine the idle speed gets to 1600-1800
rpm.After 5 min of driving and the engine gets hot the idle speed falls to 1200-1400 rpm. In every occasion the idle speed is stabilized and has not ups and downs. I have not any trouble codes. I am between the coolant sensor and the stepper motor as defective parts but i don't know which one... Any advice how to check those parts or others parametrs would be appreciated. For better conclusions this engine does not have lamba sensor.
Thanks in advance Vaggos
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Just change the coolant sensor, the stepper motor costs about 20 times as much...

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I have already change the coolant sensor but still the same problem.... Another aspect might be the throttle pontensiometer.... But still don't have any error code..
On Sun, 5 Dec 2004, Alwik wrote:

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