I've been referred here from another ng. Here's what I posted there.
My son has an N-reg Fiesta Mk 3, 1.1 litre petrol, which is in good condition except that the engine can stop at any time or sometimes revs like mad to frighten old ladies at the traffic lights. It is now at the stage where we daren't drive it more than a few yards.
Our local friendly garage has changed a few bits but his next guess is the thing under the air cleaner - a single point injection unit, I'm told. I bought one off ebay, but when it arrived it was a carburettor, so I now have the money back.
I have rung round every local scrap yard to no avail.
It has been suggested by an American friend that in their cars, these things have a throttle position sensor, which is a small electrical potentiometer that is a likely failure point and can be measured with a multimeter.
I'm a bit crippled at the moment and really don't want to be looking at a rusty engine, so I thought maybe someone here might know how easy it is to check out this pot, or might know somewhere likely to have a complete injection unit lying around.