its possible that the tfi module is buggered. ford had big problems with this module in the states which would fail when overheated. I believe they had a civil action on their hands cos of it.
it is easy to remove as it is bolted onto the dizzy. go on this page to find out how you can test it
to remove it all you have to do is loosen the bolt that holds the dizzy, its behind the dizzy, towards the back of the car. stick your hand in and you should feel it. then just rotate the dizzy anticlockwise a bit and you should have a clear access to the screws holding it in. bewarned though, that once you do this, you'll mess up the timing and you'll need a timing gun to set it up correctly again.