R56 1.6 Diesel Bad jolt at 2300 rpm
 

My 2010 1.6 diesel, with the PSA engine, runs perfectly with plenty of power, but, when the revs hit 2300 the engine gives a massive jolt then runs smoothly through the rest of the rev range. The engine management light has never come on, I have scanned with Ista+ which only showed 2 faulty bulbs and a friend scanned with his Snap-on tool which showed the same minor faults. I havw swapped the throttle pedal, removed and cleaned the throttle body.
Has anyone experienced this problem?

Davy