One thing you may want to check is the Power Valve. If the Power Valve Diaphragm is leaking it is possible liquid fuel can run into the Power Valve chamber, through the diaphragm leak, and into the the intake manifold. When you remove the Power Valve cover thet chamber should be dry. If there is any evidence of liquid fuel being present the Power Vqlve needs to be replaced. You can get a new Power Valve with its gasket separately, but as long as you have the carburetor off it may be a good time to rebuild it and replace its old gaskets. The 2100 and 2150 carburetors are very easy to rebuild, and they are reliable devices. That said, I would not begin turning any screws here and there unless you relly know what yo are doing, As for the idle air.fuel mixture adjustment screws, I suggest you turn them in (clockwise) until they seat, counting the number turns needed to seat them. Do not force them to close when they seat. Then remove them so you can let the carburetor cleaner get into its channels. When you replace the idle screws, seat them gently, then turn the screws out (counter-clockwise) the number of turns they had taken to seat initially. If you did not count the # of turns from being seatred, yo can begin with the 2 1/2 - 3 turns out from being seated as a starting point.
There is a lot of information on the Internet about carburetors, and a lot specifically about 2100 2v carburetors, to include a lot of How To videos in YouTube. So much information that I have never felt compelled to document how I set them up and adjust them. Google and YouTube are your friends.
