eratic engine revs on my g200 charade

Forum: 

Hi guys n gals , i am a newbie to here . i have problems with eratic iding etc with my g200 charade Unknw When i start up and its on choke the engine revs to around 2000rpm until warm then it settles at around 1400 rpm , once its been driven for a few miles the tickover revs up and down itself , any idea Unknw could this be the idle control valve many thanks in advance