Assuming it idles reasonably I would tend to think it is a fuel supply problem. I have experienced it before when the engine only gets enough fuel to the carb to just tick over. As soon as
the throttle gets openned up it draws on the last fule in the float and dies. Unfortunateley from there you will have to chase it. As stated in previous replies, it is usually something
simple. e.g. fuel filter, dirty float bowl/seat. If your filter was dirty maybe a little got through into the carb? Generally components like fuel pumps last for a very long time and when
tiring starve the engine only on full throttle. If you have access to compressed air a quick blow through your fuel line between the tank and filter will confirm that it is clean. Sometimes
a fuel line blockage along the car shows symptoms like a dud pump.

Let us know how you do. Hope this helps?

you state you gust got it back from being painted. Have you tried changing your plugs. I have found the plugs can get fouled due to the paint vapors. I have seen this on
several cars after they were painted.
Bob

Dear all,

I have just got my car back from the spray painter (hooray!), looks great, photos up soon.
I have no power though. I got home (1km from painter) then went for another spin.
I had NO power, i got onto the road, second gear then it started spluttering and farting about.
I switched it off, restarted and tried heading home (up a slight hill). STILL NO POWER. I limped home in first gear going about 10-15kmh.
WHATS GOING ON??
There is no power anywhere at any revs. High revs still no power (but i cuts out and splutters before high revs). Low revs (like 1000rpm) I have enough
power to limp home.
Is it a fuel problem, cause it sure seems like it. The dizzy is ok, rotor, points are all fine.
I need to get my car to the pits for rego, so it needs to go!
Any help would be great, i need to get it going over the weekend (unfortunatly working sat & sun)so I can take it to the pits early next week.