Boost loss underload- help!

Hi guys having I few issues with my car!
A1 1.4tfsi remapped @156bhp & 257nm. All is fine and dandy and pulls well through the gears HOWEVER... Put the car on an incline and at 1/2 or wot and the car cuts boost (which can be heard recirc).
Specifically uphill at 3k rpm in third and 2-2.3k rpm in fourth. I've also experienced this on the motorway at 65mph in sixth. Each time boost is cut then car starts to pick up again with no warning lights or other drama!

The garage that mapped the car have already changed the boost control solenoid, but to no avail.
Also I'm running standard dv valve exhaust etc

Any ideas would be greatly appreciated

So your thinking is something like overboost caused by less than ideal settings(boost/torque limits) over something like a boost leak or coil pack starting to fail?