Which carbs are you running? Unless you have downsized the carburetor(s) considerably from a single one, you'll never be able to get a good idle mixture adjustment. For instance, two carbs for a 134 cubic inch 4-cylinder CJ-2 Jeep will only be a little over-carbureted (268 cubic inches) for a stovebolt engine, not MASSIVELY too much, like two 235 carbs (470 CI). Even running a pair of 216 carbs would help the situation a little. A couple of Motorcraft carbs for a 170 cubic inch Ford Falcon engine might work OK.

A Uni-Syn tool measures airflow, not mixture. It needs to be used with all the throttle linkage disconnected, and the throttle bell cranks held against their stops with small springs or rubber bands. Once the airflow is set correctly on both carbs and the throttle linkage has been reconnected without changing the idle speed, then you can tinker with the mixture screws.
Jerry

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