coil or alt

Thanks

None of the above

Check fuel system , ignition system . From your description alternator and charging system are okay .

Update,

Fuel filter been changed recently?
Crap in the carb(it is carb?)
Fuel pump working ok?
If filter bad,fuel filler neck ok?

Oh and check the air filter is ok and pipes to it

is it revs related? ie at x revs no matter the speed it always runs like a dog? if so it could be an ignition fault.

for the priceof parts i would try and new dizzy cap, arm and lead and coil,

where did you last fuel up? has the problem been on going before your last fuel up or just since the last, just a thought

I reckon you have a rusty fuel filler neck or crap has got into the fuel system. When it happened to me it started off by the car being unable to get above 60-70 and then over a period of a week or so it just would not run well at all. Check that first (filler neck) and start from there. Classic symptoms

When I got the car the filler neck was rusty, i have since replaced that.

Anything else I should do? Do I need to get old rust out of tank? If so how?

Hi, This was the story of my Clipper. Turned out to be dirt in the fuel tank
(from the neck and fuel) which was blocking the tiny holes in the suction
strainer in the tank. You will have to remove the fuel sender under the rear seat to check. (Take all usual petrol handling precautions).
This leads to starvation. I opened up the holes and replaced the in-line filter in the engine bay. No more problems.
Keep smiling. J

I don't think you have a battery problem but also don't understand the 65amp and the connected and unconnected diagnosis.
J.