Giving it a shot here too...

Here is the thing.
99 B18C1 with ITR tranny in 96 EK using 96 SOHC Vtec harness and OBD2-OBD1 conversion harness with chipped P28.

Car started right up without a CEL but idle is bouncing between 1000-1500 when warmed up. Runs really nice

All the vaccum hoses are ok, nothing cracked or leaking.
Disconnected the IACV, threw a code and idled between 1500-1600(engine is still cold)
Reset ECU, replug IACV and same thing, 1700-2000rpms idle.
Engine rev real nice when giving it some gaz, does not stutter, bog or whatever.

Ok... still doing it and it's starting to bug me BAD...
What i've done so far...

-purge system to make sure there are NO bubbles anywhere.
-looked for vaccum leaks...
-switch ECU with a known good one
-looked for vaccum leaks...
-readjust idle as per manuals, cant get it to idle lower then 1100 even with idle srew fully in...
-looked for vaccum leaks...
-when I unplug the IACV idle goes to 1100 and purrs like a kitten
-looked for vaccum leaks...
-Did I mention I looked everywhere I could for vaccum leaks?
-Nothing except the TB and the IACV has been tampered with on the intake.
-the TB gasket is new
-the IACV o-ring is ok, I added a slight coating of sillicone to make sure.
-All ground are excellent(1 on head, 1 on tranny, 1 on intake manifold)
-Still no CEL except when I unplg the IACV.
-Remove T-fitting from manifold to FPR and IAB, now only 1 tube straight to FPR.
-Cursed alot...

Anything else I forgot?

Next step is to try another IACV(found one tonight) otherwise I'm clueless... BAD...

Any other vaccum nipples on a GSR manifold except lower driver side where FPR/IAB connect, behind where brake booster connect and close the the TB flange poiting to the firewall...

HELP...

Thanks alot for your help!!!!

 

Yes, you forgot a couple things that could possibly solve your problem

Take off the IACV sensor, grab some brake/carb cleaner and clean the screens on the IACV.

Another thing, look underneath your throttle body, and you will see the fast idle valve. There is a gold looking plate behind it held by two 8 mm screws.

Remove those screws and the plate, and you will see a plunger looking diaphram with a spring loaded white plastic piece.

Turn that white spring loaded white piece clockwise all the way until it is tight, then put her back together, and start her up.