sometimes after tunrning the bug off i get some run on which may just be a spluter or has sometimes gone on for an embarressingly long time. wat cause this and wat can i do to fix it?

We had exactly the same problem.

Changed to premium unleaded and it stopped.

That simple.

Lots of suggestions about what it could be if that doesnt work.

Here 'tis

http://www.aussieveedubbers.com/forum/viewthread.php?tid=35053#pid303454 

some causes are

too low octane for the comp ratio
too advanced
carby style - state of tune
coked heads

99% of the time you should be able to tune it out

Do you have Kadrons?