On Mon, 20 Jun 2005 11:25:15 +0100, ChrisJ
chris@youmustbejokingifyouthinkImputtingmyrealadd resshere.com wrote:

stuff snipped

Hi Chris,

A good point to start is to check the ECU to see if it's reporting any
faults. There are a few forums around and it looks like a code reader
is easy to make or cheap to buy:

http://www.google.co.uk/search?hl=en&q=ford%20fiesta%20ecu%20codes&btnG=Go ogle+Search&meta=
http://www.preloved.co.uk/fuseaction-forums.showdiscussion/thread_id-11135/23c2a78a.html
http://www.abbeypowertools.co.uk/subprod/car-fault-code-readers-0001406.aspx

If the ECU is reporting a faulty sensor bear in mind it could be a
loose connection instead of the sensor itself. If the ECU is reporting
all OK it could be a bad sensor making the ECU get the timing or
mixture wrong, or something not related to the ECU such as fuel
flow/pressure problems.

It does sound like the faults could be due to a bad airflow or engine
temperature but it's by far the best to diagnose the fault in a
conclusive way.

cheers,
Pete