880-920-880-840-880 and repeat seems to be the idle on mine when hot. I can however see the needle move up and down ever so slightly if I watch carefully. Im surprised you guys cant see it move if you can hear it....

Maybe my gauge is very sensitive...

Ill chalk this up as normal since everyone seems to have a slight idle fluctuation..No ones seems to be perfectly steady...

Cheers,

 

OK, I paid attention to the tach after driving about 50 km this morning. The tach needle moves with the changes in the idle speed, but so little that I guess I'd never noticed it before. The needle movement is barely visible. My guess is that springer3 is correct regarding the etiology of this - it's a feedback loop. Makes sense to me.

 

Like most of your cars, my idle is audibly moving up and down, and it is barely noticeable on the tach. It's been that way since I got it (2 years), and has not changed. I've always wondered about it, but no more!