I been having iacv problem on my 99 civic si with jdm 00 gsr swap. It would idle at 1.5k and become jerky. So far I have clean and change the iacv with 4 different one, each one would work good for a day or two start doing it again. Now i dont what to do next.

here video of it idling

 

CEL codes?

Does the engine have a FITV? If so, clean and adjust it.

Have you bled the cooling system?

 

CEL is P0505. There no fitv on it. I already bleed the cooling system till fan kick on 2 time.

 

update: ok so i clean the tb and spray brake cleaner around intake manifold to try find leak but there none. i also swap out the ecu with another one to see if ecu is bad but same thing.

 

I am having the same thing and I have been working on my car for the last 2 months to figure it out and I cant get it at all. the same problem your basically having.

 

Test the TPS and ECT sensors.

 

Have you checked your PVC valve, hose and grommet ?