Sub-Zero Fluid reservoir
 

Did a quick search, couldn't find any info about it.

What is it for? It has what appears to be a vacuum line running to it, and a couple electronics. The line that runs to the carb runs to a weird looking fitting. Doesn't look like a vacuum fitting at all.

Do I need it now that i have removed all my emmisions? or is it just dead weight in my engine bay that i dont need?

Its a cold start assist that provides an anitfreeze like mixture that gets mixed into the carb
on very cold starts (below freezing or zero degrees F depending on model year). So its only
going to work on very cold starts. The FSM tells you all about it and how to test it and make it
work. You probably don't want/or need it.

This link has some information about it
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/sub-zero-starting-system-fluid-reservoir-382092/
Beat me to it tg

im going to take it out.. coldest it gets here in victoria is about -10.. and i probably wont be driving my car those days anyway.