My father in law is trying to hunt down the problem with his 1938 model 41 with the 248 cu. The car will act like its not getting enough gas when traveling at a steady speed. It kind of jerks back and forth but if he pushes down on the gas pedal it seems to run fine. This only happens when trying to stay at a consistant mph. Very noticable aroung 30 mph or so but will do it even at 55 mph. Carb has been rebuilt and the in line filters have been changed going to the fuel pump. Timing has been checked and new points installed. No change. Any ideas?