Hey there, my Fiesta has developed a problem.

When starting the car it coughs into life and sounds like its misfiring but once it's warmed up its fine, thought it might be something to do with the HT leads or coil pack but if it was it would be misfiring all the time wouldn't it?

This has been doing my head in it was perfectly fine until last Friday and it seems to be getting worse.

Any ideas anyone?