Travis Tiny Webb

I have a 2002 5.3L LT Tahoe. I tried changing my oxygen sensors via "DIY". Every autopart store gave me conflicting info on what type I needed, so I contacted two dealerships. They both informed me that the upstream/downstream sensors are the exact same on my model SUV, so I got the part number & bought the sensors from an autopart store...three times. Now, my Tahoe runs worse! In gear, idle/stop, it runs below 1000rpm, chugging, blowing exhaust smoke, I've blown two sets of sensor heater fuses, & my check engine light is still on, even after I reset it twice. The only codes I had prior were o2 sensors & Cat. converter. HELP!!