1997 Chevy Suburban Catalytic Converter

How many times have you had the catalytic converter replaced and if so when was the last time you replaced it. Is the coverter discolored or bulging anywhere? Use a vacuum guage on the manifold and run the car up to normal operating temperature. If the guage seems to slowly fall towards 0 Hg. And then rise back to 17-22 Hg. Then the exhaust is restricted. If it has been 60,000 miles then most likely you are correct that the catalytic converter is dead. By 60,000 miles the catalyst material has been significantly clogged with carbon buildup and will eventually clog the entire exhaust system. Usually this is a gradual process as the car will first recieve worse gas milage and then drivability; however, the catalyst honeycomb can collapse on itself and more or less fuse and melt together under the extreme heat from exhaust gases. Please note that an EGR valve can also cause problems similar to a plugged catalytic converter.