My '53 AUM had been idling pretty rough (wasn't getting huge fluctuations in revs, but it wasn't at all smooth and was starting to get on my nerves) - I was also having dips in power in low revs and it was driving jerky in first and second gear.
I checked all my hoses, and it turned out the hose on top of the DV was ever so slightly loose, so I pressed it right down and tightened the clamp a little. While I was at it I also removed all the spark plugs and gave them a clean with carb-cleaner and checked the gaps (had to adjust 2 out of 4 as they were slightly too narrow). Car's been completely sweet since, so I don't know if it was a boost leak caused by the DV hose not being fully connected, or whether my spark plugs weren't in the best condition, but one of the two has sorted my problem.
Could be different to your problem of course, but with a rough idle it's surely worth checking the spark plugs - do you get any flat spots/loss of power, and is it jerky when you're driving at all or just at idle?