At long last someone with the same faults did you manage to solve your problem. My local dealer has told me that i may need a new pcm unit at a cost of £800 but it may be the alternator or a short occuring in the vehicle

The car starts and idles great. occasionally it gets a really bad missfire - possibly on two cylinders?

If an electrical load - lights fan, screen is turned on, this will nearly always bring the miss on. Turning the load off, and the mis recovers after a few seconds.

the speed drops to zero at the same time as the miss starts. Can be sat on the drive to bring on the fault too.

First time it happened, an ingition coil failure code set. this sets occasionally but not consistently.

Sometimes, just driving along, with unnecessary electrics on, the speedo drops to zero the miss starts and performance is lost.

The fuel guage also drops from half full to nearly empty at times and recovers. Not sure this is at the same time as the any of the above but seems to have started at the same time.

I suspect there is more than one issue here, but it all seemed to start at the same time, suggesting just one fault. where would you start looking?

Andy I am still trying to solve this issue as yet I have not got a positive result I am about to try changing the instrument cluster which a company on the web suggested it may be. This company check ecu's and repair them etc and have reasonable rates and turn around times. I am also considering changing my battery as I that is an other possible source. the cheaper options I shall try first the fuel filter is my next bet and then the coilpack. I can only give you an update as I go if its of any use to you, as so many sggestions have been made I am progressing with caution. My local garage check for faults and cleeared my ecu as they could find nothing logged.

Andy I am still trying to solve this issue as yet I have not got a positive result I am about to try changing the instrument cluster which a company on the web suggested it may be. This company check ecu's and repair them etc and have reasonable rates and turn around times. I am also considering changing my battery as I that is an other possible source. the cheaper options I shall try first the fuel filter is my next bet and then the coilpack. I can only give you an update as I go if its of any use to you, as so many suggestions have been made I am progressing with caution. My local garage check for faults and cleared my ecu as they could find nothing logged.