[Spikesoftail]

Generaly a p0300 wont be caused by a plugged cat, its usually ignition or fuel related. Although it can be timing. An engine missfire can definatly will definatly plug your cat though. Cats are very delicate and anything causing your engine to run poorly can and will plug your cat. Unfortunatly a 97's computer is very primative as far as engine data is concerned. They are even harder to diagnose once you start modding them.