when you are first breaking an engine is you should not run it very rich, its should get up to at least 220 degree F and only be slightly rich, slightly being key word, when you take the igniter off it should run fine withoput it, if it needs the ignter, it is too rich, running the engine rich for the first tfew tanks can be really hard on it and detrimental to its life, sure it will run fine for a while but you wont get as many gallons out of it as you should, using Fuelmans way (the guy from Cooper Fuels LLC.) you will be able to get alot more power and life from your engine, right now i would lean it out and start to tune to performance and nto be afraid to drive it, dont drive it hard, just make sure it gets a workout through the rpm ranges
and the idle screw adjusts how much the carb barrel closes, if its clloses too much, at full brake the engine stall, too little and the idle is high which can make the car move without you and burn the clutch shoes