Two questions, 81 280ZX NA

[Viro]

First, should the O2 sensor have a resistance reading? Cold start, engine off or running, I get OL on my meter. Does these sensors work that way?

 

Second, see picture below. What is the part circled? It is to the right of what the FSM calls the air flow meter (labeled with arrow). It looks like a black solenoid, has two air lines going to it, and also appears connected tot he fuel system. I can hear vacuum leaking through to open end you can see in the picture.

 

 

Thank you!