2004 Chevy Silverado Code P0420 problems

2004 CHEVROLET SILVERADO
87,612 MILES • V8 • 4WD • AUTOMATIC
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PSBOWLER
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This code keeps coming up and we are running out of ideas how to fix it. Convertor is less than a year old and seems to be okay. O2 sensor #1 changed shortly after new convertor installed. O2 sensor #2 changed 2 weeks ago. Just pulled freeze frame data out and here is what it gave:

Fuel Sys 1 OL-Drive
Fuel Sys 2 OL Drive
Calc Load (%) 1.96
ECT (F) 195
STFT B1(%) 0.78
LTFT B1(%) 6.25
STFT B2(%) 0.78
LTFT B2(%) 6.25
MAP(inHg) 11.22
Eng RPM 537
Veh Speed 0
MAF(lb/min) 0.73
TPS(%) 9.41
Mar 11, 2010 at 12:08 PM
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MERLIN2021
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There is a technical service bulliten from GM to thier dealer about this. I will email it to you.
Mar 11, 2010 at 3:22 PM
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PSBOWLER
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Thanks, but no dice. Checked the wiring and no rust anywhere. Probably going to take it to the dealer this week and get it looked at again. Appreciated your quick response, though.
Mar 15, 2010 at 4:17 PM
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2 LINSEY
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Mar 15, 2010 at 5:13 PM
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MERLIN2021
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Thanks Lindsey.
Mar 18, 2010 at 4:08 PM
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