Limp Mode ????

[zakstar]

Hi all, im Zak and new to this forum and would be extremely grateful if anyone can give me some advice on my 2006 diesel X3 Sport.
Purchased the vehicle approx 8 weeks ago and was extremely pleased with it.
Unfortunately in the last week or so when i try to accelerate through 2nd, 3rd and 4th gear there is a definite rev limitation to each gear and it feels as though the engine is in a kind of 'limp mode'. the engine does not exceed 2000, 2500 and 3000 RPM in each respective gear and there are no warning lights on the dash.
I have done a little research and found that the 'diesel particle filter' may need cleaning/changing, but can anyone shed any light on this please with regard of costs etc
much appreciated if anyone can help