there's probably a green book on the k-jet site on how to properly setup that system.

 

You did adjust the idle with the idle screw (black ****).

 

Hi,
I know this is an old Thread, however, I was having the same trouble. I have the same engine in a 79' 242 dl. I followed up to the unplugging of the air regulator(which I have attached picture of). I unplugged both ports (pictured) and neither seemed to make a difference in the 1800 rpm idle. I turned the ****, on the throttle body, to the right lowering the idle to 750. I was wondering if this was a sign of a bigger issue, i.e. carbon buildup in the throttle body, etc, or just part of having an older car.
Thanks in advance for any help.
Best,
Brodie

I forgot to thank Pierce for his help before on another thread so I will say thank you here. Thanks!!!