I've been having an intermittant metal scraping noise like something tinny rubbing and rotating, under acelleration it sometimes goes away. then I wiil jump in the truck the next day and it's quiet as a mouse, there's no predicting when it happens. I have checked for loose shielding at the brakes and exhaust and found nothing, could it be the idler arm roller slowly dying? Any ideas would be welcome, otherwise the truck runs and rides smooth! 2003 4.0 Supercab Edge

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2003 Ford Ranger Edge Supercab 4WD 4 Door 4.0 liter pretty much stock except for aftermarket taillights.