2013 diesel hesitation 2500rpm+

Hi, after some sage advice please. 

I have a 95k miles 2.0D. Last 2 yrs only gets 1 run per week and usually only motorway cruising or A roads. Quite bad hesitation 2500rpm+, so much so that I prefer to overtake or accelerate in 4th or 5th and use the torque 1800-2500 rpm.

Full power accelerating and injection cleaning makes it better, but after a few hrs economical cruising in 5th or 6th the hesitation is back. No warning lights when it happens.

Amy suggestions gratefully received.

Thanks