The DPs are essentially race carbs. And as such are rather rich in the transitions. The wide open is typically okay, but on a street car, the off idle and cruise are very rich.

On a milder engine, jetting down the slots will clean that up. And then going a few steps smaller on the mains, opening up the PVCRs to compensate and then getting a little quicker opening power valve will help clean the cruise up without sacrificing performance.

An O2 sensor makes this more accurate, but can be done without it. You will have to guess and then experiment on the main jets, but you can do the math to get the PVCRs to the right balance.