Hello everyone! I've been having an issue with my 1987 300zx I picked up a few weeks ago. I got it running, but it will not idle below 1200rmp's. If I unplug the AFM, it goes down to 800, but it runs like crap. it has the Idle up Solenoid removed, I've checked the Idle air control valve, the TPS switch, and the Throttle body. I've also replaced all the vacuum lines save for the HVAC, which I capped off. Does anyone have any idea what this issue could be? It's about to drive me mad, and I'm trying to get this figured out soon so I can go smog it.