Actually the rpm issue had nothing to do with cold or warm engine , it would have "mood swings'.. At times on idle speed the RPM would shoot up.... at other times I would be driving smoothly and RPM would increase and I would feel myself loosing control on steering. It also badly affected fuel consumption.
And I dont know how to check whether it is faulty or not. and you cant check yourself , you will have to consult a daewoo doctor.