Have only done around 500 miles since purchase... bulk of this on the motorway which with average speed cameras everywhere means a steady 2000rpm most of the time. I did give it an old school 'Italian tune up' and found that it thrashing through the gears it goes quite well... but there is definite hesitation on going back on the throttle after a gearchange and definite gentle surging otherwise on neutral acceleration.. It was due a service so also changed fuel filter but no change. Im starting to think EGR maybe hence was wondering if OP had ever got to route of the problem... used an older scout 2012 with the old PD140 engine for a while and although a little noisier there was never any hesitation or surging and throttle response was very good.