Lately and more and more often my Suzuki can not stay in idle forcing me to play with the throttle

Driving the vehicle for a distance or some high rpm drive takes care of it

Then idle is normal

Later on,  after parking and re starting or upon arriving at a traffic light idle starts acting again

Then it goes away and can not bother again for hours or days

Other than those episodes , rest of time idle is fine

What could this issue be ?

Last night I drove to the airport to p/u a friend    Car started cold perfect   Drove there perfect   Parked   

After getting all luggage and back to Suzuki it started acting 

Like said before if I go fast for stretch of road it goes back to normal 

In heavy traffic in the airport loop it was not fun having to keep idle from dying