Hello to all. Need a little assistance. I own a 2004 Silverado 1500 with a 5.3 automatic 2wd. I can not get it to pass emissions due to Code P0133. WHich is O2 sensor left front bank. Replaced it 3 times had computer reset at dealer and several other mechanics excluding myself to look at truck. The only known problem is rough idle after truck is warm and at idle.
Check engine light will NOT stay off.
Does anybody out there have any ideas or has experienced the same problem..?
Help is greatly appreciated, I love my truck

Thanks,
Cash1