I have a 1987 Civic Si which is idling high - I've debugged it down to being the fast idle valve (if i hold my thumb over the hole there the idle is perfect). I've changed out the PCV valve and tried both taking apart the fast idle and cleaning it in addition to trying to just tighten it down - still no dice, so I think it needs to be replaced. This part seems unavailable anywhere, I'm a little leery of buying a part like this from junk yards since it may be just as broken, where do you all get parts and do you agree this is the best fix?

 

I would try to disassemble it and clean that ball as it needs to seal against the ring that tightens. Parts, i just use my own parts cars, so i can't recommend anything.

 

Its been a while since I have done this, but I recall a ball and a plunger on mine that I was able to clean and get to function again on my FITV.