So I've rebuilt my carb, installed new rotor, distrib cap, ignition coil, plugs, installed new header gaskets and collector gaskets. Things were running fine, but a little weak on acceleration and a rough first to second gear shift. After a lot of reading I decided to change out the vacuum modulator to see what it would do for me and it helped the rough shift a lot, and also gave me a decent amount more acceleration. I had to readjust my carb to run better with the change in vacuum and it's the peppiest the motor has ever been. Run's absolutely great. The only problem is the backfire on throttle release. When i'm under load and driving at mid to high rpm and release the throttle to decelerate (like a highway exit) it cackles and backfires out the exhaust a LOT. Before I adjusted my mixture it did the same just not nearly as bad and was manageable. I would love to keep the carb set up just how it is but I gotta get rid of all the popping. Any suggestions where to start?