Hi. I've had this problem on and off for a while now, but it's getting to a point where I'm getting annoyed with it.

The car's idle revv counter doesn't seem right, i'm not sure if it's an air problem or a sensor issue.
Whenever I knock the car out of gear and coast to a red light or any stop, the car stalls. The revvs go down to <600, the battery warning light comes on, and stalls. If i'm quick enough i can give the car a touch of gas and it stays running, and the light goes out.

I've just replaced the crankcase vent pipe because that popped the engine management light on a few weeks back. I'm not sure if these 2 issues are related.

A friend of mine mentioned it could be an air intake issue, or there's a problem with a fuel sensor. But i'd rather have the opinion of someone more specialized.

Thanks in advance

P.S Can you dumb down your responses for me

 

How old is the focus and is it petrol or diesel?

 

1999/2000 and Petrol.

 

When you say the crank case vent pipe has been replaced was it the one that goes from the right hand corner of the engine (near gearbox bell housing)to the inlet manifold ?

 

http://www.ebay.co.uk/itm/New-Genuin...-/360784038582

There was a split in the previous pipe, so i had that fitted.

 

Could be an idle speed control valve issue?

 

that is the common one that splits causing a fast idle speed . You could try dis connecting your battery for a bit and re connecting to see if that cures ?

 

Odds on it's the vss, vehicle speed sensor.