Q: Truck runs smoothly with no misfires but CEL is on and bank 1 is running too lean.

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I have a 2005 ford F150 (5.4L 3-valve Triton V8). Last week my check engine light came on. took it to autozone to get the OBD reader on it. there were multiple piston misfires. I got all new spark plugs and all new ignition coils, and replaced them all myself (didn't break a single plug) and today I took it up to autozone AGAIN because my CEL came back on. Now they're saying my fuel filter is bad and I need a new one. No big deal it's $20. and they also said bank 1 is running too lean. Possible cause was labeled as a bad MAF sensor. I've spent about 5 hours on the internet gathering as much knowledge I can about this P0171 thing but I need the opinion of someone who knows about this kind of stuff.
My car has an automatic transmission.

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