Engine Performance problem
2000 Chevy Express V8 Two Wheel Drive Automatic
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im trying to help my freind with his van . he says at times it runs very slugish and the check eng light cam on had it put on a OBD tester and it reads fuel trim bank two cond. explanation , the ECM has detected a rich or lean air/fuel ratio cond on eng bank two. probable causes - 1- if bank one and two are set together suspect a fuel condition or MAF sensor fault .
2- failed HO2s21
3- ign misfire cond.
4- fuel injector problem
5- engine mechanical cond.

can someone please elaborate