I have a mk6 02 plate fiesta 1.4 Duratek engine, 68,000 miles.

A few months ago my engine management light came on. The fault was found to be a rusty ignition cable and an engine misfire on one of the cylinders. The ignition cable, coil pack and spark plugs were all replaced at the start of September. Over the last few weeks every so often the engine management light has flashed on for a few seconds and then gone off again. While this happens, the car struggles with power and then it is ok again when it goes off.

Any advice on what could be causing this would be a massive help as the garage I have used haven't a clue!

Thanks