Hello and thanks for your very good page you have.
At first I am sorry for my bad English.
I bought the Focus second hand therefore I am not sure about the Mileage.
My problem appears only when I start the engine and the car is out of operation for hours e.G one two nights, and never when is hot.
So my story : When I start the engine the idle is little up the 1000rpm and my thought this is normal.
Now, after few seconds maybe one minute and when I brake to stop the car the idle fall too low (more than the normal and I am not a new driver) and the engine shake like tend to stall and then without do anything the idle return to normal (about 800rpm). This maybe happen for two three times (from the time I start engine) and then as the time pass and I drove don't appear again.
I want to mention here that the needle after all these I said above and after the idle falling is little very little down the 800rpm but stable.
Summarizing: only happen when the car is cold and when I am braking to stop the car - after few minutes of driving doesn't continue to fall the idle too low and shaking the engine when I am braking- the idle after all these (and I mean I'm driving e.G for 10-15 minutes) is stable in little down the 800rpm indication.
Thanks for your time
I look forward for your answer !