I have a 77 280Z with 5 spd manual trans. The engine was rebuilt and runs great when warm. Cold starts are fine (cold start valve is operational) but I need to keep my foot on the peddle to keep the revs up when cold. As soon as I let off my foot it stalls. Warm idle is fine. Is there a cold idle setting that I can adjust?

Likely a problem with your air regulator circut or the air regulator itself. That's what controls the cold idle speed.