Hi friends, I'm back with a new problem
2008 Sport automatic with 58k miles (yep, very low). This week in Chicago, temps dropped into the 30s, and the Fit started idling rough - little jolts / stumbles. It does this on cold start and doesn't improve when warm. Once moving the engine seems perfect - just an issue with idle. I bought the car this summer and this is the first time this has happened.
I've poked around this forum a lot, and based on these symptoms and mileage, I had the valve adjusted today. Both intake and exhaust were significantly out of spec (my mechanic was pretty surprised by how far out they were).
The engine audibly sounds better and feels great when driving, but the idle is exactly the same as before - no change.
I had the plugs replaced when I first bought the car (Denso Iridium).
Where should I look next?
Thanks!!

 

Ignition coils and recheck the plugs (make sure that they are tight)
If this will not solve the problem unbolt EGR valve (but leave if connected) and cover the flange with metal piece

 

Seconding the ignition coils. Don't cheap out, get the Hitachis (they're the OEM, but you can get them cheaper than they'd be at the Honda dealer).

 

I changed all four coils yesterday (Hitachi), engine is running perfectly now. Thanks!!