1991 Honda Accord intake manifold

My car will start to choke when gets up to 4th gear on the the meter on the left side on the dash board so I had some one look at it because my car was stolden and I had to get a new catalytic converter put on cuz it was stolen as well but the mechanic said I also have to get a intake manifold gasket because there was small leak in mines and he said air was getting out so im tryna locate were and what the intake manifold is and can I fix it my but I cant find it