Freelander 1 td4 loses power

I've owned my freelander for about a month, it's fine to drive until I go onto a fast road then it loses all power struggles to go uphills or maintain 50mph, once it's gone the power stays poor at all speeds in all gears, until I turn of the ignition then once started again even if only turned of for a second it will run great again until I reach 45 to 50 then it will lose power again, I've changed the maf and I've ran with the maf unplugged I've given it a full service, I've changed the intercooler hoses for silicone hoses and now I'm stuck, any help would be appreciated, I'm sure I'm not the first its happened to, love the car just wish it would let me do dual carriageways, it's an 03 freelander 2 ltr td4 with 93000 on the clock, any ideas ?

Look in the freelander section of the vehicle forum.

https://www.landyzone.co.uk/land-rover/td4-lack-of-power-at-70mph-fixed.77147/

There's a whole thread on this issue and how to fix it.