Discovery Td5 bad fuel consumption

[George]

I've got a 2004 Disco Td5 (125000km) and got some weird problem these days. The fuel consumption is very bad (6.5 - 7 km/l) and power not on 100%. We've checked about everything already - diesel pump, injectors, airflow meter, no errors on ECU, turbo, but to no avail.

Anyone else had a similar problem or perhaps know what the cause of this could be?

Thanks
George