So I've had this going on for I don't know about a month I'm not sure when it started I only noticed it if I have the windows down and I have like a concrete barrier or something that the sound can echo off of but there's a rattle and I'm pretty positive it's right about under my feet. driver side pedal area but you can tell it's like under the car, or at least that's what it sounds like but the weird thing is it only happens when I let off the gas if I press the gas it stops immediately and it also doesn't seem to happen at lower speeds although I haven't figured out exact speed parameters or range I was debating whether it was a heat shield rattle although I haven't noticed any Loose Shields as best I can see or if there's any rocks or anything in there rattling around. or could it possibly be the exhaust cooling off after I let off the gas but I mean it happens even when I was just barely hitting the gas so I doubt that's it but you know sometimes you get that tinking noise as metal cools but again I doubt it's that since. I looked up rattles but I didn't see anything that was exactly like this but it did seem like in other forms there were quite a few EcoBoost that had something fairly similar but I never saw a solution or what the cause was. Does anyone definitively know or has anyone had this something similar happened and found out what the cause or solution was if you want to offer suggestions that's fine too but please only give a solution if you're sure or like you had some similar happen and you had a solution to work for you I'd love to know about any of those.