hey jay i have a 2.4 bp question

ive got a 91 bp with carbs and today i was running about 5g and in some huge waves on lake michigan and took a few hard slams after the last one my motor felt as it lost more than half its power real boggy then it shut off and would not fire again. once back at the house i checked all plugs for spark and it was ok fuel to all cylinders is ok as well. i got it to fire but again felt as it was running on 2 cylinders and sounded horrid and would die a soon as i let off the throttle. After geting pissed i started messing with stuff and this is where my question comes in. there is what seems to be maby a brass cylinder with a knurled knob and spring coming out of the bottom of it located next to the carbs i noticed it was backed all the way out so i turned it up 3 times and tried it again now motor seems totally fine runs good idles good like nothing happend. I asuming that this is a idle screw? just wanted you opion on this and if it make a differance when geting on plane i sometimes have to choke the motor because it bogs down and dies? maby because that screw was all the way out? i havnt got to run it again yet to see if its better. thanks alot for your help