I personally think it the tentioner,,,it's plain ole wore out.
You need a total rehab,,,pulleys, belt, and tentioner.
When that noise happens when it's rev-ed up,,,does
the timing belt flutter up and down between the cam gears?
If so ,,definately need a complete over haul of the timing
components,,,don't skimp and but this then that if it doesn't
fix the noise,,,,buy the all timing components and balance shaft