Hello.. 

Hoping someone could help 

I got a Vauxhall insignia 1.8 petrol 

I got a problem where it hits temperature it start hunting/misfiring 

it runs perfect to it hit temperature 

Don’t know if related or not 

But when you removed dip stick or oil filter cap it trying to stuck air in 

All started from a map sensor what has now

Been changed 

If is occurs at a specific temperature then I would advise changing the Coolant Temperature Sensor as this would cause similar issues at a specific temperature.
Not too expensive to replace and should be an easy enough job to do