If the engine runs better with choke than without it, it is running lean. That probably means that either there is an intake air leak at one of the carburetor insulator gaskets, or an obstruction in the carburetor. You did not say that you had taken adequate measures to fix either problem.
I suggest that you take the following specific steps. First, remove the carburetor. Then remove the insulator (the thick plastic part between the carburetor and the engine's intake port) and replace the thin gaskets on both sides of it.
Second, strip the carburetor again, but this time clean it out with a spray can of carburetor cleaner. As an experiment, I once tried to clean the main jet of a GXV140 carburetor without using this cleaner. I washed it repeatedly in petrol, and probed it repeatedly with the standard jet cleaning tool (an oxy torch tip cleaner of the largest size that will pass through the jet). After a fair amount of work, I was able to get a 0.45 mm tool though the jet, though it was a tight fit. Then I sprayed a quick blast of carburetor cleaner through the jet. Instantly, it would freely admit a 0.55 mm tool. The GXV140 suddenly lost all its symptoms of slightly lean mixture.
You can't remove built-up gum from a jet by mechanical cleaning, or by the use of mild chemicals. You need carburetor cleaner. You also may not be able to get the emulsifier out of the carburetor - they are prone to getting stuck in place due to hard gum formation. Whether or not you get it out, in addition to the main hole in the far end (at the carburetor's venturi) it has a dozen tiny (0.35 mm) holes coming out of it crossways, and all of these must be able to pass air freely for the carburetor to give the correct mixture. Unless you keep the carburetor wet with carb cleaner for long enough to soften the hard gum so you can push the emulsifier out, the only way to try to clean those tiny holes is with blasts of carburetor cleaner through the threaded opening where the main jet screws in. Even then, I think your chances of being fully successful are not good unless you actually remove the emulsifier, and clean it in detail.
Did you remove the plug above the idle jet, and clean that jet also? I've explained how to do that in the other thread I referred you to.
