Right,changed the carb for one i ordered through ebay.Cleaned,fitted & doing the same.So it wasn't/isn't the carb 
I've noticed while letting it idle that revving it becomes worse the longer it's been running.Say down from 3000 to 2000 revs & starts missing & spluttering.
There's no smoke from the exhaust & on idle..low revs sounds fine.
Running out of idea's Could it be the distributor? The vacuum advance on it seems to work fine.
HELP!!!
