Running cold on motorway, not thermostat :/

[porka]

Hi guys, I have a strange problem with my 04 3.0d.

Arround town, the temperature very slowly gets to normal, about 88c and on the motorway it drops down to barely over 60c.

Simple I thought, dodgy thermostat, so I replaced it today and no change !

Whilst driving and keeping an eye on the digital temp. readout under option 7 I noticed something very strange.

Below 2200 rpm, the temperature gets to normal and above that it shoots down

Basically just under 70mph normal temp. and at 75 its gets down to 60 odd, crazy !

It's as though the thermostat is opening at higher revs, but how is that possible ??

Maybe someone has come across this before ?

Thanks for any help !