Hi again all I have a 57 plate focus 1.8 petrol duratec he engine it ever so often has an idle problem where I slow down to the lights put in neutral and the revs go up to about 2500 then down to about 500 with the battery light coming on does it a few times then cuts out.

I have read about cleaning the throttle body out etc. Is there any common faults on these to check it does not do it every day and normally when it's still warming up to tempature 

Thank you again Simon 

Maybe change the throttle position sensor? Can these be changed 

Any help please 

Still.doing I have replaced the runner control valve all ready HELP

Gibbo. Have you tried unplugging the throttle body sensor plug on the engine. Spray wd40 on it and plug it back in. I had idling problems on my 1.25 fiesta 2004 for years and spaying the sensor plug fixed it.

On 1/5/2020 at 7:14 AM, gibbo1471 said:

Hi again all I have a 57 plate focus 1.8 petrol duratec he engine it ever so often has an idle problem where I slow down to the lights put in neutral and the revs go up to about 2500 then down to about 500 with the battery light coming on does it a few times then cuts out.

I have read about cleaning the throttle body out etc. Is there any common faults on these to check it does not do it every day and normally when it's still warming up to tempature 

Thank you again Simon 

The other common faults on this engine are:

• The PCV valve and hose perish and stop working, the parts are hidden inside the inlet manifold so the whole manifold has to come off to replace them.
• The 2 valves that control the runners can fail, although from the Op's more recent comment it looks like they've been changed.