help needed with a 2L hdi 136bhp question?

[barrym028]

I have an 06 307 2.0l hdi 136bhp with the six speed box
A short time after acquiring the car it started to to have problems,
The mil light came on with depoultion fault with intermittent loss of the turbo, and a surging at around 1700-2000rpm
Scanned and got fault code related to maf sensor and the turbo repeat sensor. Both items have been replaced and faults cleared from the ecu.
Turbo seems strong now and no fault code or waning lights, but the surging at low rpm remains, it can be over come by accelerating harder.
I'm at a loss as what could be causing this any help would be great

 

[barrym028]

The turbo repeat sensor is set correctly at 11% with the ignition on and the engine off,
am I right In saying that the turbo on this car won't spool up fully if the car is not in motion? Reason I ask is the the pipe work from the turbo to the intercooler to the inlet manifold doesn't get as hard as I would have expected when revving the car in neutral.
Could the egr cause this are should I be looking elsewhere, maybe a vacum leak or something else?