2008 Basic Fit 137K miles

Has a noticeable miss at idle and just about 2500 RPM. Tachometer moves slightly downward.
No codes. No power issues.

Does not miss when load is being applied at higher RPMs (air conditioning on, accelerating, or operating above 3500 RPM) -- only misses when accelerating below 3500RPM and at idle.

Was initially thinking it was transmission slip when I was highway driving. But it happens on idle about every 30-45 seconds.

Plugs and coils replaced approx 2 months ago after code popped up for #3 coil pack - spark plugs were shot. \
Read about the loose plug issue in the forum post -- first I heard about it. Going to pull coils and check plugs today if I can.

What to check or replace: (Basic things that I am thinking of)
Replace air filter?
Check for vacuum leaks with carb cleaner?
OPen and clean the throttle body intake?
At 137K miles, should I go ahead and replace injectors? Something anyone can do?

No engine light or code(s). Hoping to run this vehicle another 140K. Until coils/plugs replacement it was only brakes, tires, oil changes and fuel only. Most dependable car I ever owned.

Any thoughts or experience shares would be appreciated.
Thanks!!

 

Have you checked and adjusted the valve clearances?

 

Bingo! At 137,000 miles, it is 77,000 miles past due for adjustment.

 

you get it fixed or what?