Hi, I haveFord Focus MK1, 1.8 zetec, 2000 plate, petrol engine.

I had faulty spark plug, after a service and on a very short journey home the car was coughing and spluttering, obviously missing. I found and replaced the faulty plug (number 1 for ref.), along with the ht leads. Took her out on for a motorway shake-down run and she is still chugging and coughing during acceleration. Once I got it up to speed, it ran pretty well cruising along.

The car starts first time, is not cutting out on idle, speedo reads fine, no warning lights, although I can hear a mad fast clicking (like the indicator click) behind the dash during acceleration. just coughs under any sort of acceleration (light or hard) I think the coil pack is next to replace and check the fuses. Any additional ideas anyone?

Thanks in advance.
Rich