Looking at this from a simple perspective, likely culprits are a loose connection somewhere or as has been suggested, heat getting to something and causing issues.

Have you tried the plug leads? I had problems until I switched to bosch leads as some others can be nasty.

Damp is another issue but that should go away after 30 mins of driving and the engine getting hot.

Another thing could be the heat expanding metal somewhere and opening up a crack or similar? Could be internal.

I feel for you, these problems can be soul destroying and expensive to chase down! If you can, maybe transfer all your coil, leads, dizzy, carb and so on, onto another 2.25 and see how it runs. May be a lengthy process but a morning should see it done. you just need a willing subject in running order!

well I fitted a new Hall effect dizzy from simonbbc and it made a bit better running than the accuspark dizzy I had on.

think I found why I was getting rough running though-fuel line had collapsed under pipe clip!

moved fuel line today as when I was stood still in hot weather I got vapour lock (engine died on acceleration...let foot off and away she went)

ran fuel line away from engine..fingers crossed it won't get too hot



also put an egr blank in my 1.6tdci focus

That will help a little but in the end I binned the mechanical pump and fitted a Facet electric one (low pressure) and a pressure reducer. Don't bother with the cheap pumps from ebay they break after a week!

The ethanol in the petrol boils and locks the valves in the top of the mechanical pump - it might be possible to replace the metal plate for the pump with something made of plastic but you'd probably still run into bother in a hot weather jam. I've just got back from le Mans and several hot sweaty 2 hour traffic jams, if I'd still been on the mech pump that would have required a good few cool down sessions with the bonnet open - like all the MGs!