I have a 1948 8N with front mount distributor and converted to 12 volts about 3 years ago. Put on a new carburetor two years ago. It has been starting and running reasonably well since the new carb. It wasn't used during the month of September. I tried starting it in early October and it took a long time to get going but finally started. I ran it for about 15 minutes, although it seemed to be running rough, and then it stalled and wouldn't re-start. I left it for a bit and tried again, I flooded it so I pulled out the plugs and cleaned them. It then started but was almost continuously backfiring. I put in new plugs and the problem remained. It also seems to be flooding very easily. Any ideas?