[Slopey1939]

Greetings,
I hope someone out there can give me a little advice on this issue. So, a 39 Fordor Sedan Deluxe, flat head V8 (motor might be later 40's) normally getting about 14+ miles to the gallon highway suddenly dropped to about 7. Symptoms are: idling a little bit rough, vacuum gauge shows 1 inch fluctuation from 20 to 19 and back, more when idle increased, more soot than normal out of exhaust pipe, some surging when being driven, plugs are black as heck but dry. My guess is a carburetor issue. Has been at least 15 years since a rebuild. Any chance of fuel pump leaking internally? No outward fuel leaks anywhere.
Thanks very much for any help you can provide.
Dave