So I've got an issue where the car (280z 1975) starts up well from cold, idles at about 900-1000, but the idle quickly falters after about thirty seconds or so, going down to 500, where the car promptly dies.

However, once the car has warmed up (after about ten minutes, or five minutes if I turn the car off, wait and start over again), idle stabilizes at 700-800, and... Everything's fine

So while I'm waiting for the weekend to tackle the issue hands on, theoretically, this sounds like it would be the auxiliary air valve stuck in the shut position?

It's my understanding that the cold start/thermocline should only affect the engine for the first minute or so, which is probably why the engine runs fine initially... Am I on the correct track?

Further, is there any way to repair/open the AAV or am I stuck getting a new one if it's broken :?