Ford fiesta 05 1.4 enige warning light and missfire?

check the ht leads,and coil pack if you leave it to long it will blow the pcm[brain],take it to a ain dealer,after you have replaced the above items,also check for water ingress onto the rocker cover the washer jets leak onto the engine and the water gets onto the ht leads there are modified jets to cure this known fault,there maybe a software update on your pcm,again check this with your main dealer.