I'm back again and now I have a fully equipped new exhaust system w/ front/rear CAT, O2 sensors, and a engine coolant sensor. NOW, my truck rattles where the exhaust is when I'm idling at a stop light/sign along with a rotten egg/sulphur smell from car. The mech, says I may have more fuel and less air flowing thru. fine, what needs to be replace? All the sensors? what other sensors are there? Or isit something else from the egg smelling odor? I LOVE this truck but this is really pissing me off. All awhile I'm still getting a P0420 reading ONLY.