Easy check:

Blank off ERG system pipe at the air inlet end; not the exhaust end. It's the corregated stainless steel pipe joining the engine air inlet top left. I made an aluminium plate to blank the engine side and a wooden peg and elephant tape to blank the pipe end.

Take car for a run. If fault has gone away then problem is EGR valve or its connections to the EGR cooler. These pipe connections are metal to metal joints sealed by metal clips and if they leak they can cause loss of turbo pressure with hesitation particularly when cold. I sealed mine with Hylomar.

Second hand low mileage EGR valves are can be found on E-bay but it is worth dismantling and cleaning your own valve first. Use a felt tip to mark the position of the black fork spring housing before removing the 3 bolts attaching it to the body. If the spring loaded fork sticks at all, replace the valve. Don't attempt to dismantle the spring housing; it's a pig to put back together again.

Good luck.