Runs Rough in Cold Weather after engine warms

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My 2000 Silverado 5.3 starts fine in cold weather(below 20F) and runs great until it warms up. This has been slowing getting worse the past several winters. The engine light comes on every winter(if I clear the codes, it comes back as soon as it comes up to operating temp). The engine really surges and sputters at stop lights. It runs great throughout the rest of the year. Codes 171 & 174 indicate lean on both banks.