rev ur car up listen to your exhaust does it sound normal???the cat wont be glowing red unless its got raw fuel dumping into it ,take ur o2 sensor out behind your rear valve cover in the exhaust manifold and go take it for a ride and jump on it and if your miss is gone youll need a cat thats how i always check um works all the tyme,

p.s cats only get glowing red if they got raw fuel dumping into it think about it ppl if its clogged how would it glow it cant nless its partially clogged