i have a pace setter exhaust with a magnaflow strait through muffler. some of the days the exhaust sounds really buzzy, and other days it sounds nice n deep through all the rpms. i heard that buzzy noise was cuased by unburned fuel. i also cant pass emissions because im running lean. my only ideas on how to make it run right is to change the timing belt, change o2 sensor, egr valve, and advance my timing to 16 degrees. what are some more sensors that tell how much gas to shoot in??