Lack of power when cruising under 2000rpm

Hello,

I owned a Honda Accord CD6 powered by H22A engine. My problem is, when it cruising under 2000rpm its feel like not enough fuel and no torque. But if I push more throtle and increase the rpm over 2000, it get the power back.

I already replace the throttle body, distributor, plug cable and spark plug but the problem still happen.

Hope someone can help to solve this problem.

#sorry for my broken grammar.