Having an acceleration problem when I go over 30mph or floor the gas pedal. The car is a 66 delta 88 convertible with 425. Its has installed a new Holly 750 carb with electric choke, Holly intake, new plugs and new distributor with points, rotor, etc. Plugs, Timing and points tune-up were completed and the car ran great for about a week. Recently, when if I go over 30mph the car will hesitate, seems to want to stall and backfires. The backfiring seems to be in happening in the exhaust. Any suggestions?

 

Have you re=checked the dwell?