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I was receiving p0171 and p074 codes ONLY with CEL activating after approx 10 miles of driving. During driving and upon stop always strong smell of unspent fuel from tail and at engine. Many vacuum leaks repaired including elbow end at PCV hose on back of valve cover. Also replaced clogged fuel filter and bad cop #7. On every repair the same two codes returned with CEL with unspent fuel smell still apparent. Finally replaced what appeared to be PCV valve in good working order. Cleared the codes and performed idle relearn. Drove approximately 9 miles when engine acted as if missing and dropped to 500 rpms at stop. Engine continued in this fashion for approximately .5 miles than cleared with idle rpm at 750 constant. Drove another 6 miles with no return of symptoms and NO CEL. Do not smell unspent fuel when driving or at stop and shut off. Scanned DTCs and have the codes listed in question in pending status. Should I clear these codes and continue driving to determine if there are really issues?

Vehicle: 1998 Ford Expedition 5.4L triton Eddie Bauer 4x4

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Clear the codes even if its pending, when you clear the code it restart the ECM long trim.Drive it as you would normally and recheck pending codes,  Here you can verify the repair.

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