PebbleBeach

I am a new member. I have a 2000 Gs300 with 37K miles. I noticed that the engine is very noisy in the morning, the problem goes away after the engine is warm up. It is pretty cold here in the morning. But not freezing (Oregon, USA). Also noticed the RPM is around 1400. This drops to about 500 after the engine is warm up. Is this normal for a GS300? I would like to know if anybody has experience this and have any recommendations. Thanks a lot