As far as the science shows, Sorghum Malt works well as a base malt and can be used for converting adjunct grains, though the amount of adjuncts needs to be carefully planned.
The sour note that you mention seems to be a natural flavour of Sorghum coming through. Most on here either mask it with adjucts and other fermentables, hide it with other flavours or use specific hop schedules to compliment the flavours. It has also been noted that extended aging seems to take the edge off the sour bite and mellow the flavour.
Have you used hops or other herbs for bittering, aroma, etc? or are you just fermenting the sorghum and sugar?