G'day mate,
Was it running ok before and if so what have you done since then. You said if you hold the distributor and turn it a bit that it runs a bit better. If you are able to turn the distributor with the engine running ( over the normal movement for the vacuum advance )the lock bolt on the back of the distributor may be loose. You should start by setting the ignition timing and see if that makes a difference and then work from there. Do you have a workshop manual?
Cheers
Bob
