The problem is you only know when a coil pack has failed when you change it for a good one there are some tests that can be done but of limited value.
Fixed a similar problem on a 1992 MX5 the other day and it was the temperature sender that supplies the ECU with readings to decide when to put the electronic chocke on.
It was giving the wrong readings. In that case the simplistic diagnosetics gave 9 flashes on an LED.
On that car there was another sendor to feed the electric fan.
A friend uses one of these with his laptop on older Fords.
http://www.ebay.co.uk/itm/Ford-F-SUPER-d...=item234338644d
