Idle adjust on '73 1.7 Options

[socal1200r]

Stock engine, but idles VERY low, even when warmed up. On my throttle body, there is a flexible rod with a plastic knob on top of it, and when I turn it the idle changes. I can hear more air being sucked into the TB when I turn it counter-clockwise, and when I turn it all the way clockwise there is no air sound, and it idles so low it almost dies.

What exactly does this rod do? Is it for the idle adjustment, or fuel/air? The reason I'm asking is if I use it to adjust the idle, the car doesn't run very well, in that it will stumble and backfire if I use it to set the idle to just under 1K. If I use it to adjust fuel/air, I can get it to the point where it runs pretty good, but idles at the lowest mark on the tach when cold, and just above it when warm.

Any ideas? And yes, I did do the search function, and it appears that this flexible rod thing is to adjust the idle, but I just wanted to confirm with some newer replies.

Thanks