So I just bought a 91 Camaro RS yesterday for $500, When I went to look at it , it would crank but it wouldn't stay running. when I got it home the first thing I did was take of the catalytic converter after that I took of the air cleaner and fired it up, with the air cleaner of it would idle kinda of high but idle nonetheless. anyways I noticed there was some kind of air flow sensor or something going in to the bottom of the air cleaner I just assumed that was the problem. I guess my question is what the hell is this thing and what does it do ? I currently have it hanging of to the side and the car is running alright.

I have another SBC that im planning on boring out and putting a 3.75" stroke crankshaft in. I want to get the engine that's in it currently running right so I can sell it and make a little money back. I have also never dealt with a carbureted car before since this is my first project.
any help would be much appreciated

thanks