1997 Sonata 2.0 Fuel Trim Malfunction (DTC P0170) - Diagnosis and Fixes

I own a 1997 Sonata base model with a 2.0L engine. About two weeks ago, I performed a tune-up using Bosch diagnostic equipment. Last week, my OBD-II scanner detected DTC P0170 — Fuel Trim Malfunction (Bank 1). The car does not run rough when idling, but while driving it feels sluggish. I've heard that a faulty oxygen sensor could be the cause. Could a used MAF (Mass Air Flow) sensor also contribute to this issue? I'm looking for clear steps to diagnose and fix this problem. Any advice on what to check first or how to verify if the O2 sensor or MAF sensor is at fault would be greatly appreciated.