Air flow sensor issues

Hi,
I have a 3.4Lpetrol 95 series prado (2000). I am travelling around Oz for the year and had an air flow sensor problem in Adelaide.
The car intermittently lost significant power and acceleration. The problem worsened to the point that the car wouldn't go faster than 50km/hr with foot flat on the accelerator.
It got changed and the problem was immediately fixed. Interestingly, the diagnostic tool never came up with an error code.
Since Adelaide, we have done about 5000km and are now in Geraldton. Done some off roading but nothing too extreme.
The same problem has reared its head but is very intermittent. I have cleaned the air flow sensor and it hasn't helped. The air filter was changed recently and isn't very dirty.
Just wondering, is this likely to have happened again? The air flow meter was a genuine Denso part and expensive so I don't want to get another one unless I really need to.
I know this model is known to get contaminated air flow sensors (looking at forums) but this seems ridiculous. The mechanic in WA said it is a very rare problem and an air flow sensor hasn't been sold in WA for nearly 2 years!
Nothing at all comes up on the diagnostic tool again and the car is otherwise running fine.
A mechanic in Geraldton suggested it could be the fuel pump but the 95 series has a fuel pump for each tank and the problem occurs independently of which tank I am using. Surely it is unlikely that both pumps are failing.
We are heading to Darwin and will be doing some pretty remote driving so want to sort this out before heading into the wilderness. If we were staying around a big city, I wouldn't even care.
Any thoughts would be much appreciated.
James