Hi, I'm having some engine issues. Whilst out shopping the other day my fiesta started to sound spluttery on pulling away,  also seems sluggish too. Could this be the coil pack breaking down,  or something more sinister??  I thought maybe timing was out but I'm not sure now. Any ideas would be appreciated. 

Thanks in advance Andy. 

Hello,
check coil pack resistance.when you changed spark plugs and high voltage cables?
At evening you can open hood and using water mist check if there is no spark running around engine.
 

On my Mk1 it was the coil pack I also changed the plugs and  HT leads worked a treat no more problems.

Coil pack prior to 2006 are inclined to fail.

Coil pack. Also change the windscreen washers. If the back seals are leaking, water on coil pack.

I had a similar problem with mine, turns out it was more likely to not start when it rained. As mentioned above if the seals are broken on the windscreen jets then water can get in to the coil packs. My mechanic said this is more likely on the focus but can happen on the fiesta. After he took my coil packs out, cleaned them and sprayed them with what i believe was silicon spray it has run perfectly since. If the coil packs need replacing this is a job you can likely do yourself with new packs, HT leads etc bought on ebay. Never done it myself on the fiesta but if it is anything like on the punto it is a quick job.

thanks everyone for your advice. It turned out to be the coil pack breaking down on one side. Ebay took the strain, and £9.99 and 3 days later it was on my doorstep. Replaced very quickly, then a good run into town down the A11, and all is well. It has even stopped the idling fluctuating at junctions. I am a happy bunny now.