Driving down the motorway at 75mph my engine suddenly lost power dropped to 50 mph - foot to the floor would not pick up. After 2 miles it picked up again and felt Ok but not as powerful as it should. Next day when cold the car started first time but appeared to rev itself - seemed OK when warmed up, but again a little jerky. May not be related but my temperature guage has been going up and down for a while, but normally returns to normal. Any thoughts?

Quite a few, need some diagnostics done to pull up fault codes,

Possible

Sticky turbo

Coolant temp sensor

Air mass meter.

had something v similar on mine - it was the air mass meter - repaired under 2nd owner warranty

To finish .... Air Mass Meter replaced EGF valve blocked off, drives like a dream again