It can be super frustrating when you're trying to get everything just right and it's not quite working out. From what you've described, it sounds like you've tried a bunch of different wick sizes and still haven't found the perfect fit. One thing to keep in mind is that wick sizing can be affected by a bunch of different factors, like the type of wax you're using, the fragrance oil you're using, and even the environment you're making your candles in. That being said, I've heard that IGI 6006 can be a bit tricky to wick sometimes. Some people have had luck with HTP wicks, but it sounds like you've already tried those with mixed results. Have you tried using cotton wicks instead of the pre-tabbed ones? That might give you a bit more control over the wick size. Another thing to consider is the fragrance oil you're using. Some FOs can affect the way your candles burn, so it might be worth experimenting with different scents to see if that makes a difference.