?? Weber 32/36 DGEV vs 38/38 DGES 1967 Volvo Amazon

I made the switch to a larger carburetor. It&a Weber 38/38 synchronized 2 barrel DGES with electric choke and oversized jets. I need to rejet it but it was an instant improvement in power. My fuel economy, even with it running super rich is still about 23. The 32/36 was 23 to 26 mpg on its best days. I am still having in issue with leaning out at light throttle, almost like a failing accelerator pump, but the pump has a new diaphragm and sprays strong. The dgev did the same thing last month on the way home from ft collins, and only got slightly better when I replaced the accelerator pump diapragm. Perhaps an air leak somewhere?