my check engine light came on the other day, so i had someone show me how the manual readout (without the diagnostic computer works. the code said it was a faulty oxygen sensor. so i checked the header downpipe and the gasket was burnt out and that was were my exhaust gasses were exiting the motor. so i fixed that, and now its still reading a faulty oxygen sensor. i needed my car, so i just unplugged it whenever it started bogging down or idling rough (wich are the symptoms that ive noticed) and it runs ok. but yesterday, i pulled up to a friends house and shut the car off because it was idling rough, and it would not start. im wondering if the fact that i cut the back muffler off (because i was planning on running one pipe out the side) and my resonator is full of holes, that maybe that might affect my oxygen sensor. now, the car starts really roughly. and my parents hid my haynes manual, so i figured that someone on this site would have an idea of whats going on.