Need help on a rattling sound that is happening on my 2006 f-150 screw 5.4 only mods are volant cold air intake and cat back exhaust. Sound seems to be coming from passenger side foot well compartment. Its sounds like a spark knocking or tinny sound only when engine is under load . First experiance it when od is off and im pulling a hill with my trailer, Now i seem to hear it when truck is in od and climbing a hill when the rpms go down before it kicks down . This noice is really annoying sounds like the truck is going to come apart. Any help would be greatly appreciatted