Sometimes my engine feels like it's misfiring. It happens more often in high gears and the engine gets loud. The power disappears completely. Sometimes it works fine, but has been ocorring more and more often, though? I have heard my cat might be clogged and there is a plug that I can pull out of the Catalytic converter to test it. I wanted to double check on brickboard to find where the plug is located and if these symptoms might be indicative of another underlying problem. The sparkplugs and air filter are all new and the plugs are gapped properly and not fouled. Also, any ifo about vacumm line diagrams would help.