Jon, there was another post on a similar fault last week, basically the car goes dead when slowing down or stopping at junctions. If it's the same problem as mine (306 xsi) this was how it got resolved;
"Turns out the idle motor needed a good clean, mine was pitch black and after cleaning it and running a cloth around the slot it fits into my car now works fine (ticks over more smoothly than it has in a long time)."
Thanks to Paul Westney for suggesting the idle stepper motor on a previous post.
Not sure if this is the same thing but hope this helps.
Hello there
> just occasionally - maybe two or three times in the last year -
> the engine on my 306 XSi has died unexpectedly. This has to date
> always been during short local trips. It's unnerved me partly because
> the of the loss of power steering, and I've been worried about it > happening at speed.
>
> A little while ago, during servicing, my garage mentioned that they
> had to replace a fuel stepper motor. Since, from reading up on this
> newsgroup and elsewhere, it seemed possible that this was the problem,
> I thought 'great - I should be OK now'.
>
> However the engine has died on me three times this weekend. I was
> again getting unnerved, but I just realised that on each occasion it
> happened, I was slowing down at the bottom of a slope, prior to
> turning. Also, I was low-ish on fuel - I tend to run the car on the
> 'low fuel' light a bit.
>
> So, the engine always seems to die when slowing down, and always when
> the front of the car is lower than the rear. I can't be certain that
> fuel was low on the other occasions, but it is possible.
>
> Is the explanation simply that the engine is dying due to fuel
> starvation (and I should be more prompt about adding petrol in
> future), or is this likely to be a symptom of a fault elsewhere in > the fuel system?
>
> Thanks for any thoughts
>
> Regards
> Jon N