Au v8 idle-WOT hesitation

[Jack91]

Hi all,
Picked up a donor for my Bronco. I drove it first and didn't notice this or it happened on the 4hr truck drive on the way home.
I have a 1-2 second hesitation when I snap the throttle.
I have tried-
Fully drained and cleaned tank, cleaned pump sock - wasn't dirty
Added 40L of 98 incase it was bad fuel
New fuel filter
No air filter
Plug and unplug, clean and inspect maf, throttle body, intake air sensor, no change.
New coil packs
New plugs
Sprayed all around intake manifold to try find a leak.
I'm really stumped to what this could be, but I want to get it right before removing it.

My options are:
Replace maf, O2 sensors, intake air sensor, fuel pressure regulator and hope for the best after $600.
Then try get a cheap 044 incase the pump is dieing.
If still no good, intake manifold gasket but I really don't think it's that.
Im only using the motor, loom, ecu, radiator and thermos so trying not to put money into this car as it's destined for scrap.

[Jack91]

I only mention O2 sensors as i can't think of what else controller fuelling, and between those, the maf and iat sensor it should cover all bases.
Car revs and performs well if you don't snap the throttle wide open

[Bossxr8]

MAF could still be faulty.