i have '97 sc300 hallowed cat been running wo cat for abt 5 months and it was fine, well taken care of. when i accelerate from 2000-4500 RPM and let go of a gas it makes the "bbbrrrrrrrrrrrrrrr" noise. WTF is it?? hooked up OBD-2 reader, shows- 2 oxy. sensors? but would the car even start if it was oxy sensor?? every day its getting louder and louder little by little but it still drives fine, its just makes me feel nervous cuz of some shit might go wrong down the road. PLEASE HELP ME. or reply with email or number so i can contact you and see whats up if you can help me. THANK YOU