To help with my understanding, could someone describe the differences they've observed between smooth and rough at idle?
My Honda is less than a year old and to me at idle it just sounds like it is not the sweet spot for the engine (primarily more vibration). But it doesn't sound like there are fuel delivery issues. I'll have to try the partial choke trick next time I fire it up.
In my case I've swapped back and forth between the high-altitude jet since last year we visited campgrounds at 7,000 and 10,000 foot elevation. And based on my pre-purchase research I found non-ethanol gasoline locally and put Sta-Bil in from day one.
Thanks for your input