My 89 came to me in boxes. I’m trying to figure out how the idle adjustment fitting on the intake manifold is adjusted. I don’t know if all the parts are all there.
In this picture the o ring is in the wrong position,it belongs below the flat surface of the long tube ,as you tighten the large threaded nut it compresses the rubber o ring to constrict its inside diameter to limit the amount of air passing thru it.most people dont now how to adjust the idle speed on these cars .Alot of times the oring is so hard it will not collapse and you cannot adjust the speed at all. only after you replace the oring will it adjust correctly. Good Luck Paul
My '86 Graduate does not want to idle below 1200-1400 when warm. Replacing the thermostat in the housing now shows 175 degrees water temp when warm, and runs better. I found the o-ring at the bottom of the threaded area