Thanks for that. I don't pretend to fully understand fuel injection
systems - I'm an electronic service engineer, so well familiar with
faultfinding procedures and the problems of intermittent faults - but I do
understand them enough to know how they work, basically what all the bits
do, and how they hang together to form a closed loop system with the EMU.
Many of the electronic items that I work on have similar closed loop servos
in them. My feeling was that it was electrical, and that the throttle
position sense pot was a possibility. Anyway, thanks for your input. I have
printed it off and just dropped the car back in to them, and they were very
interested in what you had to say, so we shall see tomorrow ...

Geoff

Thanks Rodan, more valuable input. Year is '98, miles approx 86k. I too fail
to see how engine RPMs can *appear* steady when engine is idling lumpy, but
trust me, that was what I saw. I had driven today to nearby town - 8 or 9
miles - and it had been doing the almost stopping routine. I did my banking,
and popped in the cake shop and then back to the car - say 10 minutes. It
was a bit chilly, so I started the engine, and left it running, whilst I ate
my cheese and onion roll ( not relevant, but makes the picture more
interesting ... !! ). I had a cup of soup on the top of the dash. Suddenly,
the engine started to idle so badly, that the soup cup slid forward on the
dash until it touched the 'screen ( car was parked forward pointing down a
moderately steep hill - come to think of it, might be a red herring, but on
this particular run, the place it starts doing it, is where I first
encounter a traffic queue, and it's downhill ... ). At this time, the rev
counter was indicating 900 RPM, and it didn't move by as much as a needle
thickness during the whole episode. Now that is actually a bit strange in
itself, as all the time that this problem has existed, the revs have been
able to be seen to be bouncing up and down slightly, which was never the
case before I started to have problems. I don't know if the garage did a
retrain of the EMU after replacing the IAC valve. I know that it was
certainly driven around by the mechanic that fitted it, but I think that he
based his conclusion that it was " just the same mate " on the fact that the
revs were still hunting up and down a little, and this was the '
ever-present ' symptom of the fault, rather than the almost stopping, which
I don't believe that they have ever witnessed. Can they reset the EMU with
their magic OBD box, or does it require a full battery off reset to initiate
a retrain ? The reason that I ask this is that the radio has not required a
recode on each occasion that I have got it back from them, which would
suggest tha the battery has not been off ??

Also, interesting that you say about the coolant temp sensor. A friend of
mine had exactly this on an auto Range Rover that he owned, and which had an
almost identical fault to my little Ford. The EGR valve possibility is
interesting too. I wasn't aware of this component, so just did some reading
up on it. Quoted faults for it sticking open, sound very like the symptoms
that I have. Do all EFI engines have one of these ? I've never noticed
anything that looks like the picture I saw, on my engine, but perhaps I've
never really been looking.

Anyway, thanks to both for the comments and suggestions so far, and keep 'em
coming ... All much appreciated !!

Geoff