CRV 2002 starting RPM malfunction

I asking for a starting malfunction with my CRV 2002 manual transmission : When, in the morning, I start the car the RPM goes to up 2000 instead of 1500RPM that usually I have observed, after a minute when the car is getting worm , the RPM start to go UP and Down from 1000 to 2000 RPM with high regularity than after 5 minutes the RPM is fine and stable at 600 RPM. The problem appear come out only when the car is getting cold.

Somebody can help to understand what append to my CRV

many thank in advance

Giuseppe-Italy

I have had similar things with different vehicles I owned and never paid attention to it.

May be more knowledgeable person will chime in and correct me.

Sam