Tinny engine rattle at 2-4k RPM (video attached)

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Hi there, it's my first post! 

My 2012 Aygo MK1's engine (1KR-FE) runs smoothly in idle, under 2k RPM and over 4k RPM, however it makes this alarming noise around 2-4k RPM when rev'd in neutral, and under certain conditions while driving. I've owned the car for a couple of months and it had it since I got it.

Video: IMG_0812.MOV

When driving, the noise doesn't seem to be tied to RPM but appears across a certain range of travel of the gas pedal position a bit past light foot pressure, but once you press over that range it disappears again. When the car is driven while minding this certain range of travel of the gas pedal, there is no problem even if revs visit the same areas (2-4k) - it's only within this certain range of gas pedal travel. It's most audible at 1st & 2nd gear, but becomes barely noticeable at higher gears.

The vehicle's service history is near perfect, there was only a single gap where it was driven 15k kilometers (9k miles) past the oil service period, and it did have some nasty spark plugs.

Now I had the old oil + filter & plugs replaced. I also did both an electrical & mechanical inspection of the VVT solenoid as it apparently is susceptible to clogging if the oil is bad.

Something to note as well is that the noise hasn't changed in quality at all despite the car being driven daily and there is no warning lights, OBD fault codes or power loss, the car drives perfectly. No smell of burnt oil or whatsoever. 

The noise seems to emanate from near the throttle body.