Just a thought as I've done the above myself!!! Lol

Just seems odd that you've tested for breakdown on plugs/leads, dizzy cap is new and all the cam/ignition timings are correct but it's weak on just one cylinder - not come across that before

Ok, here's another idea then....just in case it may be fuel ie: too much/little rather than the spark strength, try doing an injector swap and see if you can make it misfire on another cylinder. I'm assuming that you've taken the plug lead out and it makes no difference on no.1 so it should be very obvious if it fails on another cylinder.

Just a thought....