Problem with "hottering" or engine loss of power at speed

Hi everyone - my lovely Freelander 2 (63 plate with 73K miles) developed an issue while driving home from holiday this weekend - we have been in the lake district - so lots of hills and slow moving traffic - then on the motorway at speed we had what I can only describe as a power lapse - the car kept moving but it felt like a couple of blips - a bit like a deep breath then back to normal - any suggestions? I had a new fuel filter at the last service in May - I spoke to a garage who suggested that I trade it in for a new one ( not helpful) so any help or suggestions would be great - nothing is coming up on the dashboard - no warning lights or anything.
Diane

My defender does that sometimes, just a momentary blip a mile or two after setting off. I think its when the engine has warmed up and the thermostat in the cooling system opens, and the coolant temperature sensor tells the engine management system somethings changed and it hesitates while it sorts itself out. It doesn't bother me when it happens, its not a problem as far as I'm concerned.

If its only done it on one occasion then its going to be difficult to fix. Whatever you change may not solve it and you won't know anyway if its just a one oft event. Ideally we need it to happen more regular.