I haven't heard of the leave-in method - I may try it, but some other people have had success with using Conditioner only, Condition-wash-condition, and other variations. Also, when they use the conditioner, they use the conditioner as a cleaning agent and do a scalp scrub with the cheap/silicone free conditioner. You get small suds if you do a nice finger-pad vigorous scalp scrub with the conditioner.
What I do is mix baking soda and conditioner together. I add brown sugar on occasion.
Perhaps you're using too much baking soda or you need to dilute it more. Some people do baking soda and honey (and/or conditioner).
You'll find all kinds of experimentations, products, recipes, and whatnot on the first page of the Curly Girl thread in "find your tribe". Check that link out.