90 civic with poor combustion engine

condition : engine with 350000 kms and internal engine damage maybe caused by bad valves, and compression rings.

trying to maintain idle by turning the idle screw above normal 800 rpm
caused a surging engine

the following is what i have gather or assumption

ECU will cut fuel to injector in order to conserve gas when rpm is above normal with thottle posiiiton closed . example when vehicle is slowing down

ECU will open injector once rpm is under normal 800 rpm thus causing the surge

rpm is determine by distributor signal

how can i maintain high idle without surging ?

the only time that i do not see a surge in rpm is when engine fan on

You should have you valves checked out along with your rings. Your valves could have mushroomed tops, or even warped face.

Some idiot mechanic that worked on my car set my idle at 1200 RPM and it was fine, except that it was wasting fuel.