I had the same problem with my 1999 2.0 Xedi after approx 75,000km. Dealer found the problem after 3 attempts. The breather pipe from the air filter to the turbo charger collapses when the turbo is operating, due to the suction created by the turbo. This was occurring under either hard acceleration or at motorway speeds - I.e. when the turbo is operating (2600 - 3100 RPM). Taking your foot off the power slows the turbo down and reduces the suction pressure allowing the collapsed pipe to open up again. The solution is to replace the pipe. Hope this helps.
I bought a second hand 1999 Freelander. 78000 miles on the clock.
As the car came from the UK, it was impossible to check the history of the vehicle from Malawi. The interior and body work was in very good condition.
First what happened to the vehicle was the fuel pipe broke right at the injector carriage pipe and the car burst into flames. Putting out the fire, I fixed the wiring that was burnt and modified the fuel pipe going to the injector pipe. Then I changed the oil in the engine to find that the oil was like syrup. Starting the engine with new oil, smoke was bellowing out the exhaust.
I stripped the engine down to find the oil rings were seized on the pistons. I did a complete overhaul, which was very expensive considering that spares are a problem here.
I must add that we can't blame Land Rover for the engine, because we do not know how the previous owner drove the F/Lander.
2000 miles later the clutch bracket broke and damaged the slave cylinder; not too bad, which I was able to modify the bracket to correct the problem totally.
A diff mounting rubber and the viscous coupling gave in as well. Replaced both.
I must say, I was ready for some trouble buying a second hand vehicle, but expected worse at that mileage and being a second hand er. All vehicles have their weaknesses.
The good side of life:
I have owned and driven many cars and 4x4's, including rebuilding a Range Rover up from scratch. I have never driven a vehicle so comfortable on long trips e.g. Malawi to northern Zambia and back a few times, still feeling good and doing all that work on the Freelander from front to back, it's one of the most robust vehicles on the road.
Land Rover always had a good name, and I hope that Land Rover all over the world could listen and read the comments to bring themselves back to the best 4 by 4 by far.
Good luck, wish you well Land Rover.
We need you back.