when ever it gets round to this time of year the wifes 1.8 focus struggles to start ,normally it fires straight away but when it gets a bit colder you have to crank the engine for around 10 secs,it then manages to fire but seems to run on 3 cyl for a few secs then it settles down to normal,after this first start of the day its perfect again and will start instantly till its been stood o/night again,its as if some cold start sensor isnt working,any ideas chaps?