Idle surging issue...and yes I searched before posting.
 

92 Civic LX with 309,000 miles, all stock except the CAI.
So my idle is surging from 500 rpms-700rpms when it gets warmed up(idle is fine and steady when car is cold).
I have cleaned the throttle plate and opening.
I have cleaned the IACV.
I checked my CAI filter, its clean, no debris, hardly any dirt in the pipe.
I have checked the coolant in the bottle and radiator..they are both full.
I even attempted to get whatever air bubbles out tonight if any(just in case).

One thing I did notice was when I was trying to get bubbles out(heat on blast, rad cap off, front of car tilted up a bit), I noticed when I turned the heat ON the idle surging would STOP..and then I turn the heat OFF the surging would START AGAIN. Is that a big clue?

I have Googled and Googled and can't find what to do next or what it means.

Please Let me know... Thank you

Re: Idle surging issue...and yes I searched before posting.
 

Warm up the engine, turn off the heater / AC, lights, radio etc. then unplug the IACV and check that the speed drops to much less than normal, about 450 rpm (this would be shaking a lot and almost stalling). Adjust the air screw to achieve this. If it cant be brought to a low speed with the IACV unplugged, find the air leak.

Unplugging the IACV will turn on the CEL with a code 14, this is to be expected.