Dirty throttle body?
I'm not too familiar with your car...does it have a throttle body? It's quite common to have throttle bodies build up deposits around the butterfly valve that chokes off the air flow, resulting in poor idle on a car that othewise runs fine. If this is your case, the throttle body bore and valve need to be cleaned with solvent and a toothbrush. The deposits won't "melt" off - they need to be scrubbed well. Clean until you can see an even ring of light around the closed valve when backlit with a strong light.