The plot thickens. This might get interesting.
Drove 150miles to a ski resort today, drove like a charm, never missed a beat, and returned good MPG.
The last 2km is a fairly steep climb, sat behind someone in 3rd quite happily.
Coming home, Car warmed up whilst i packed my stuff/skis on roof rack etc.
Set off down the long hill, in 3rd at around 30, OFF the throttle the entire time ( on the over-run if you will)
Got to the bottom, gave it some throttle, and it instantly starting missing, felt like more than 1 cyl. Changed gear, same. No miss with clutch dipped. engine man light on.
Stopped, checked code with reader, Misfire detected cyl1
Reset, and it was fine all the way home, including easy driving, and some far more spirited stuff.
Surely there is a clue here, must be a vac pipe or similar ?
The only other thing i'm thinking....More sinister......I'm loosing coolant at a fair rate. between max and min in 200 miles.....