1966 Plymouth Valiant /6 & Holley 1945 carb can only get to idle at 1250rpm. How to get a lower idle without dying?

a follow up question: does it have to correct motor mounts to keep it off the frame? and are the insulators in good shape?

it'd be terrible to get a new pan in there only for the same fate to befall it.

(i know this doesn't help you with sourcing a new one)