The other guys have posted some good things, you made changes and now have issues. If the carb worked well before, I would be looking first for a vacuum leak. What are the engine specs? What curve did it have in it before? Few things to look at with the carb after you eliminate the others, with the idle speed set right pull the carb and make sure you have about .020 transition slot exposed in all 4. insufficient amount can cause a slight stumble. Obviously no slack in the accelerator pump adjustment at idle. And if all else is well, try going out 1/4 turn on the mixture screws. And if the carb set for an extended time while making changes you may have had some gaskets dry out, something plugged...