P0171 (Lean Bank 1) showed up about a month ago. I did everything:
-Replaced fuel injectors (had a set of factory injectors)
-Cleaned then replaced MAF sensors
-Replaced intake manifold gasket (found a mouse nest under the manifold)
-Replaced the Bank 1 A/F sensor (i.e., pre-cat O2 sensor)
-Smoke test - no leaks
-Disconnected the battery for about an hour
The LTFT is under 10%, but still elevated in comparison to Bank 2.
It usually takes a couple of days to throw the CEL, but I am scanning regularly for pending codes. Nothing yet.
Next step: replace the fuel damper assembly on the Bank 1 Fuel Rail if the LTFT keeps rising.
Since I am not running lean on Bank 2 (i.e., no P0174 and LTFT is close to 0%), I'm ruling out a bad fuel pump. However, if the Bank 1 fuel damper is clogged, that may be restricting fuel to those injectors.