Junkythecat

I managed to round the nut on the erg tube attached to the intake manifold. Its going to be a pain in the butt to remove it. Is there a way to close of the tube without removing it? I assume that leaving it would be a vacuum leak. It is a 95 miata , if that is relevant. Also if there is any good ideas how to break the nut, i'd appreciate that to.(though i'm guessing it'd be trying all the normal things from google.)
Thanks! Alex