41 Ford rough running, backfiring, and hard engine vibration

[Ggmac]

Lets start .
Have you taken a compression test ?
Correct firing order ?
Plugs new and gapped ?
Are the four that running on one side or 2 on one side and 2 on the other ?
What carb ? Any adapters ?
What distributor? 6 or 12 volts ?
Have you used a vacuum gauge , if so whats the reading ? Is it steady needle ?
More to come , but basics are needed
Sounds like a vacuum leak .
What year or version of the flathead ?