GU TB45E Loss Of power Issues

Hi Everyone,
I purchased a 2000 Model GU , TB45E and 5spd box.
Surges and loses power on Fast take off on the road, and when going up inclines which are bumpy it will do the same.
MAF has been cleaned, fuel pump , sock and new filter installed and the issue remains.
Drives perfectly fine on the road apart from takeoff.
Fuel consumption is fine, engine timing is spot on and it starts and idles without issues.

Mechanic checked fuel pressure when the pump was replaced and all good there according to him.

One thing I have noticed is that the throttle seems a bit sensitive, on and off power at slight throttle movement but otherwise seems fine.

I have tested the vehicle off-road on a series of inclines. Loss of power nose first but can spin around and reverse up the same hill with full power.

Tank has been checked, no debris getting caught in the sock but otherwise not sure where else to go from here.

Vehicle has a snorkel, next thing I will check is obstruction there, but not sure what else to look at.

Any suggestions would be greatly appreciated. Found a few similar threads on another Patrol forum but no solution is listed.

Apologies if this exact thing has been covered in these forums as well, I did a search and came up with nothing so if there is a relevant thread point me in the direction :)