Hi Good Morning !
I am facing this problem for some time now. I checked this with our family "basunnahe" and his view is that this has nothing to worry.
More about the issue, car gets a >2000 RPM when I switch on at "P" and get down to 700-800 when I changed to "D". RPM gets normal after continuous 15-20 km and idle stays around 400-500. What I have noticed is this problem comes when the engine is cool and with the heat it goes off.
Some background, car is an allion 240, 2003 with 120,000km on the meter. Oil levels are maintained at required levels but not sure about descipline of the previous owner. I did a tune up and changed all plugs 6 months ago.
Is this really a something nothing to worry? Look forward for some opinions from learned friends.
Thanks.