Hello I have a 91 accord lx and I am having some idle issues.
Ever since I bought the car ive had a surging idle once warm that bounces from 900-1500. Sometimes it does it other times it doesn't or it corrects itself.

Its recently been doing it after I replaced the upper intake manifold.

Ive replaced the idle control valves.

I did notice today that when I adjust the idle screw on the upper intake manifold it would stop. Is there a proper setting for this screw or an o ring that seals it? It seems that it is causing a vacuum leak or its out of adjustment.

 

You really shouldn't have messed with the idle adjust screw. Now, after you fix your underlying issue you will need to adjust that back to spec.

Start here..

Cleaning IACV, FITV and TB - Honda-Tech

 

It was the issue... The screw was lose and creating a vacuum leak causing the idle surge. After adjusting the screw the surge/leak went away but it keeps coming lose.