I started this post about a tower .40, I did find after going through all the screw turning the following did correct the problem.
Remember I have been working with small engines like this for quite some time and this engine simply did not have enough latitude on the low end for adjustment so I enlarged the air bleed hole in the front of the carb and got the range needed for the engine to be adjusted properly. This only after knowing of several people trying the same thing first.
I tried everything before drilling and the engine would simply not run right but after the drilling it runs beautiful.

Miloh.