I have a manual transmission accord (H22A engine). Now I get an annoying problem (although it is not critical). While I am driving and planning to decelerate the speed. So I release the pedal acceleration. The rpm will go down around 400 (makes it sound like want to shut down), before it goes up again to normal rpm (around 800-900), and then it runs stable. It will happen again everytime I decelerate the speed by releasing the pedal. Some people said it is because the actuator/servo is dirty. I even had it changed with a new one. still I get the same annoying problem.
Please somebody have any idea?

 

Most likely it's the idle air control valve -- either needs cleaning or replacement. If you do a SEARCH on the subject, you will find many detailed responses.