Does the throttle valve switch give continuity at both idle and WOT positions? Also, does the microswitch on the accelerator linkage work properly? Both signals are necessary for the engine to determine that the car is at idle.

The coolant temperature is measured by resistence, and the manual gives two values:

20*C: 2.28-2.72 kOhm
80*C: 290-364 Ohm

In my case, a high idle cold was caused by a malfunctioning microswitch.