You didn't say where you are but if you are where the weather is warm and you are having those problems I would say you need to take the carbs off and take them apart and thoroughly clean all of the passages in the bodies and boosters out and then reaasemble everything, reinstall the carbs, and then get after it. As far as cleaning out the booster air bleeds etc. just use welders wire cleaners that they use on their cutting tips. Soak everything in an aggressive solvent like acetone or lacquer thinner before and while doing this. I say this because I am in the process of restoring AFBs all the time including 3361/62-3804 409 carbs, and when I am done always flow test completed work on a test stand engine. I am in SE Texas where it is warm from April-September and when starting the engine with a fresh set of carbs all I do after installing the carbs is blip both throttle arms two or three times, give the gas a minute or two to vaporize in the intake runners (usually the engine has been sitting a few days and the runners are dry), and then start the engine blipping the rear throttle arm mebby three times as it starts. After the above the engine usually just sits there and idles. In the colder months I do the same thing but also hold the choke flap closed, slowly opening it, to pull a rich mixture in as the engine warms. If you are constantly having to blip the throttle to keep the engine running when starting it something is either plugged up and you aren’t getting enough gas, or the idle speed screw is too far out and too little air, and fuel through the idle circuit, is flowing to allow the engine to idle.
When it is cold as blue blazes I will squirt starter fluid into both primary throttle bores in addition to the above when first starting the engine on a fresh restored pair of carbs. What I call the “carb shop” in my building is climate controlled but the open shop area where the test engine is located is not.
Your idle mixture screws should be 1 3/4 turns back out from all the way in. A starting place for the idle speed screw is 1 1/2 turns in from where the tip of the screw just touches the idle speed cam and begins to move it and this will probably be too fast.. The specs shown on the Carter factory spec sheets for the 3361 and 3804 primary carbs are .1015 primary jets. .0635 and .069 secondary jets respectively, and 3362 metering rods .0635x.069 and 3804 metering rods .063x.073. As someone said though the jets and rods you have are fine for idling because the idle circuit doesn't work off of them anyway. The fuel does pass through the primary jets but thats all.
