Hey Scott, I've a Honda Fit 2007. Randomly like once a week, it has fluctuating idle problem, dropping till 500rpm and bouncing back to about 800. This occurs only on the 1st engine start for the day within the first 10 minutes.
If it was me I would take it to a place like AutoZone and have the charging system tested for free. If nothing is found there, I would test the fuel pressure. As Scotty said in one of his videos "Test don't guess, when fixing your car"
Hey Scotty, forgot to mention I've already clean the throttle body like the way you do, changed IAC valve, coil pack and spark plugs. I also noticed sometimes when braking, the rpm dips really low and stop by itself, but the engine was not cut off and rpm bounced back to 700 and holds steadily there. All these problems are gone after a good run at high way. So don't really know what's wrong with the Honda.