High Idle

I bought this car used. Had 100,000. Now it has 160000KM. When I start in morning, it idles at 1500RPM and then gradually comes to normal i.E 600 RPM. But when I am struck in traffic stop n go situation, the idle starts to rise gradually ( As high 1500-2000 RPM) while the temperature remains constant. After driving when I put the cark in park, the idles jumps to 1500 RPM. If I have to restart the car soon after shutting it warm, it idles high.

Just did a recent tune up and cleaned throttle body.

Please advise, what can be done.