F-150 1998 4.6L 4x4 Rattling Noise Engine When Revving Up. Why??

It happens only when i rev up, specially above 3000 rpm. it's louder between 2nd and 3rd gear.
It usually stops when i stop revving up, let's say i go up to 3000rpm and i stay there... the speed still goes up. but as soon as i step on gas again to go 4000rpm, it starts again.
it's worse on sloppy roads, when climbing. it appears as soon as 1500 - 2000 rpm.
what could it be??
F-150 1998 Lariat 4.6L 4x4

[@litoid]

This is an update for everyone watching this video.
I got recommended to change maf sensor but first disconnect to try it. It improved but couldn't start moving comfortably...
So i decided to change MAF sensor used oem from ebay. And its 90% fixed!
www.ebay.com/itm/313510136755
Still sounds when gear shifts. But now i do feel the power of v8!
Video updated here:
czcams.com/video/iiny6SeJhDQ/video.html

[@Tommysmess]

Mine does this to what's the cause?