strange idling

[Ez-Geez]

when my cars running and i get to traffic lights or pullover it revs itself up and then all the way down,

can anyone help and tell me why this is ??

Dex ...

[Jamb0]

dling problems are vary common problems often faced by saxo owneres... so here are some answers to the most common idling problems...
My car seems to hold onto it's rev's for too long / my car rev's on it's own without touching the accelerator:

This could be caused by several things, but the most likely is this.
Check the green engine coolant temperature sensor (right hand side of engine), check to see if it is corroded... (see picture for location)

http://alex.insaniak.com/saxonetwork/images/coil1.jpg

If it is corroded your car will think it is colder than it actually is, so your car will over rev to compensate for this...

My car was reving itself to 4-5,000 rpm without touching the accelerator, i replaced the green sensor as it was corroded and now my car idles perfectly at around 750rpm...

To change the sensor - Undo the electrical clip, then you can start undoing the nut on it until it becomes loose enough to hand loosen... then have your new sensor ready... and swap them over asap... coolant wont come gushing out, just dribbles... is only a pretty small hole...
It's a really easy job to do... i changed mine when it was pitch black under torch light and still found it easy... The sensor itself shouldn't cost you that much from eurocarparts.com

If this does not resolve your problem then here are other possibilities:
idle actuator valve, map sensor, throttle position sensor

If problems persist please contact your local garage/citroen dealership.
My car appears to under rev/cut out and sometimes stalls when idling:

This could be caused by several problems. Your coil pack may be faulty or your stepper motor. Your spark plugs may need cleaning/replacing. Your HT leads may need replacing (only present in some saxo's).

If your car's engine management light comes on whilst your car is juddering/cutting out then i would recommend getting a diagnostics check done as it will confirm whether it is the coil pack that has gone.
I would recommend getting a diagnostics check done at a local smaller garage as they are often cheaper than citroean dealerships, and they will do exactly the same thing.. It is a simple computer check to read off a fault code.