Help. Freelander td4 losing power

My Freelander td4 Automatic 2005 loss of power between 80-120km/h. I have do full service, changed air filter, engine oil, oil filter, automatic oil, tried changing MAF sensor, all injectors are serviced and no result. Any help please. I have used fuel Additive but not result, sometimes in cold morning after starting engine cranking very very little about 1-2 seconds. How to restore the original power of TD4?

You need to check the low pressure fuel pump output pressure. This is done by monitoring the live data using a diagnostic tool. LP pressure should be over 320Kpa. Low pressure will cause low power. You don't mention changing the fuel filter which might be you problem?