Your in south africa? Your car is quite a bit different than ours.. First, you have a throttle cable right? so this issue isn't a DBW issue. What kind of intake sensor do you have? MAP, MAF, or what? IAT sensor (mentioned) could be at fault?

High idle is potentially your temp sensor, or your AC as an issue. Try turning your ac on and off and see if that effects the idle. If it is the temp sensor, it is in "winter" mode and the car is adding fuel until warm up occurs. IIRC, the winter temp is on an open loop circuit, so if you have a good scan tool, you should see it is still in open loop. Open loop does not set codes in most cars, hence why you had no codes. And if you have live data, compare the temp to actual. If you can't do any of that, just replace the sensor and see if that fixes it.