Hey guys, I'll try to keep this brief and to the point:

I have a 90 Civic with an H22a using a stock P13, and idle issues after warmup.

Youtube vid of warmup process and aftermath: http://youtu.be/hecnUg8AMuk - Jump to 4:15 if you're impatient or have seen a Honda or two get to it's warm idle.

Coolant is bubble-free.

Runs great, but I can't be bothered to constantly smooth out the idle with my right foot at every clutch-in to actually drive this beast/turd around... TIA

 

You obviously have a vacuum leak. Next thing to do is to try to find it.

 

Did you ever fix your idle issue? I just had the same deal on my 92 lude w/ 2.3. I was a dumbass and first things first i replaced the IACV which all of the forums said it was. Wrong. I removed my throttle body and adjusted and cleaned the FITV. I dont know the exact specs but from looking at prior threads and turned the white plunger all the way in (clockwise) until it stopped and backed it out 1 and 3/4 turns (counter-clockwise) and that fixed my issue. I wasted 170.00 on a new IACV when all i had to do was adjust the FITV. Good Luck.

 

Check out this thread from the FAQ, it covers virtually everything that
can cause idle probs and how to fix them,

https://honda-tech.com/forums/honda-prelude-4/end-all-idle-surge-bounce-etc-problems-thread-1979500/

 

I think my former BOOST gauge, now vacuum , removes this possibility from the equation?

Yes! That seems to be an epic thread. Dunno how I missed it! I'll give it a read now, and again once I'm completely sober. Thank you, hopefully it'll shed some light...

Thanks for your input. I'm not gonna lie, it's been awhile since I've been metally involved in the H22a/Honda thing due to some new toys, and I do remember a sensor that involved WAX during warmup...your comment reminds me of that...