you should always make sure that issues are not ignition relate prior to working with the carb, voes included. if you have a weak or malfunctioning ignition system, no carb tuning will make any positive progress. start with basics, make sure that your compression is good, test and confirm the igition system is working properly, then move on to the carb.
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More good reading: https://cv-performance.com/harley-cv...-tuning-issues
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Nice pick on the previous page Yankee Dog, I have been looking for something like that.

I have had great luck with the CVP tuners kits.

 

Yes, it's one of the best I have found. Use it all the time. I find it one of the most valuable tools in the garage. I keep electronic copies and paper copies. It comes in handy! YD

 

Not saying that ignition system is your problem, but, for the price, the Ultima 53-644 is pretty much a no brainer. $125 delivered to your door (fleabay). It is a good ignition, same as the Dyna 2000i, but lower cost. Might not be a bad idea to eliminate that part of the equation, and, the bike is probably due. Especially with an unknown history.

Tuning a carb can be challenging, but if you start at the idle circuit, then work your way up the circuits, it can help. Gotta ask, are you sure you don't have a stuck O-ring in the idle mix screw bore? Common issue. Might be worth a look. The other issue is installing the needle jet upside down (not the needle but the needle jet). Then comes the emulsion tube holes and the idle (slow) jet holes. They clog up easy as well. Just checking, YD

 

Here's a couple (better) copies of plug diagram:

 

The best tool I have ever bought for my EVO is the AFR wideband unit. (AEM for me)
It reads over three times a sec and stops the guesswork.
It is almost imposable to do plug checks properly with today's gas anyway.
Next, most do not know you have to kill the engine at load and speed you want to check plugs at.