maf sensor help please

Hi all newbie to the forum and looking for advice please. I have have had a lot of work done to my freelander td4 due to my turbo packing up the garage replaced the turbo but it didnt have any power up to 2500rpm then it was like a rocket anyway to cut a long story short i have had the fuel pump replaced with the filter the boost solenoid and boost pressure sensor the maf sensor all the vacuum pipes, air filter, crank case breather filter. they still couldn't get it right. anyway after reading on this forum and on rover rons site i decided to disconnect the maf sensor to see if that made any difference and it did the car just spluttered wouldn't rev and just stalled and from reading this isnt normal when the maf is unplugged . does anyone have a explanation for this could they have remapped the ecu to try get around the lack of power.