Say you had a stock 454, which only had a 625 Edelbrock Carb on it. Running great, timing right on. Turning 35's with 4.10 gears. Highway mileage (towing a load or not) is about 5mpg. can tow and maintain speed just fine until reaching a certain grade steepness, then just bogs out even with it floored. Nothing seems to be wrong, but for the lack of power and bad mileage, I shouldn't be getting that bad of mileage, should I?