You could call it jerking, hesitation, missing, bucking, etc. Basically it loses power for an instant when accelerating from lower RPM with moderate or more throttle and then jerks back up.

2007 Fit Sport 5MT, original owner, ~140k miles, currently driven under 5k miles per year (but has done some awesome trips in its day)

Spark plugs were done 8 years ago, but that was only 40k miles ago
Valves were adjusted 9 years ago, 50k miles ago

Tried so far: Replaced air filter, refilled with premium gas, added Lucas fuel system treatment

No CEL light has come on.

From searching other threads, it seems like spark plugs and maybe coil packs next? Looks like I could do all four coils and plugs for around $100 and there are some videos on Youtube that make this look like a reasonably easy DIY.

Thoughts or other things to check before going to a mechanic? Thanks!

 

Update: Based on many threads here, replaced the coil packs (Hitachi) and plugs (OEM Iridium) and the issue seems to be completely resolved.

 

Glad you got it sorted! My Fit is a JDM with the L13A engine and the plugs (not precious metal types) don't last terribly long. Seems like cheap insurance to replace them regularly so the coils don't get overstressed.