Holley/Demon Carb stumble
An afr meter would tell you what it needed. I love mine, honestly it was ok to get you close, but you really need to do the old trial and error thing to get the last bit out of the combo. What I really like is if the car flakes out/stumbles during the run, i look at the meter and it helps point you to possible causes. If it shows lean, fuel. If it shows rich ignition.