Ayup dairees,
More misfire problems eh ? just when you thought it was safe to go above 2000 revs... i know the feeling
especially with your symptoms are exactly what i had, i know ive commented before on here, but this time i have cured it on my car by doin the following, hope its useful to you, some things are granny sucking eggs. ive listed everything for you that i done on mine to cure it. with the symptoms being so similar as well its worth a try
this is what ive done so far :
Coilpack side :
Took the rubber sleeve off the HT springs, Stretched the spring to ensure a good electrical contact is made i stretched the spring to just come level to the bottom of the rounded collar opening on the sleeve, doused the springs in WD40 then applied some electrical conductive grease ( dow corning ) similar stuff ya put on battery terminals. Another thing to note is when you put the rubber sleeves back over the spring be sure the spring aint sitting on a little ledge inside the rubber sleeve. I found it best to pull the spring through with some snipe nose pliers completley out of the sleeve and let it recoil slowly back in
Sparkplug side :
The gapping on my new set of sparkplugs was completley out, i asked the tech dude at the peugeot dealer about gapping, he said about 1mm, with that in mind i set them to that setting, slightly tight sitting on the feeler guage as 1mm seems like a bloody lot of gap, anyways i done that meticulously and put em back in.
As a result the misfiring stopped, the only thing i would say if you wanna go down this route is to keep you eye on your sparkplug gaps, cus to me as far fetched as it sounds, the heat seems to warp the electrode arm and bugger up your gapping, as i said i set them to 1mm, i even micrometered the gap and it was bang on, after a while i took them out and checked again, theyd moved out to a gapping of around +.25mm.
other bits and pieces ( may not have anything to do with it but like i said ill list everything ive done ) :
took off the EGR valve, cleaned all that up and checked the linkage, as the one before it the linkage broke, Cleaned the MAF ( i think its the MAF, correct me if im wrong ) sensor in the throttle body, just after the air filter piperwork at the bottom of the throttle body intake, i cleaned it with degreaser, then an evaporative electrical spray.
So as a round about conclusion the coilpack HT springs are as you know a crap way of doing things, and a very weak point on the ignition system stretching them & making the entire tube conductive with using conductive grease does help, The gapping is give or take depending where you go and who tells you but 1mm gap seems to do the trick, but keep your eye on it cus mine did warp out a bit another weak point with the gap being big and the electrode arm quite long, maybe cus i run mine on a higher octane petrol ( sainsburys best )
praps making a run a bit too hot ? i dunno i just get a better mpg from it so ill carry on.
I hope some of this stuff helps ya out mate, for what its worth it has cured my misfiring problem doing that, i know its definetley something to do with the sparkplugs though moreso than the coilpack, cus not long after i gapped em, it reappeared, knowing what was going on i touched nothing but the sparkplugs, re-gapped them at tight 1mm ( tight feel on the feeler guage but not quite pinch tight ) and refitted em, took it out, and did everything i knew how to make it misfire and it didnt. the problem lies im pretty confident in saying is sparkplugs, as everything else i sorted prior to resetting the gapping again.
thats it thats me essay finished lol, hope some of it is of use, some of it blatant i know but often overlooked
good luck mate, let us know how ya get on
Only time will tell eh 
The guys said that without an indication from the computer there's nowt more they could do short of randomly changing expensive bits 
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