Misfire at idle once warmed up and code 420

2006 CHEVROLET SILVERADO
200,000 MILES • 4.8L • V8 • 2WD • AUTOMATIC
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JS69862000
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  • 5 POSTS
Misfire at idle once warmed up. throws a code 420 for catalytic convertor. catalytic convertor is 3 years old. no loss of power or gas mileage, no hesitation. new plugs , wires, computer flashed, o2 sensor are new. also compression was good on cylinders. originally had a code 300 but went away after replacing plugs and wires.
Mar 8, 2021 at 11:02 PM
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