High revs for a second on start up!!!

[low down passat]

Morning all,

I have replaced all the glowplugs with new NGK's

Replaced the coolant temp sender

Tried a working Fuel temp sender out of another car.

And still every morning my car struggles to start in the cold or on warmer mornings it will start and rev high for a second and settle down to normal idle.

Its getting to the point of doing this on every start up now cold and warm.