Originally Posted by peterj
5 ounces in 4.3 gallons is about 3 volumes of CO2 which is a little overcarbed. It's probably losing enough CO2 when you pour it so that it doesn't feel overcarbonated, but that lost CO2 is resulting in excess foam. 3.5-4 oz would have been about right for that volume.
I also agree 5 oz of priming sugar is too much for only 4.3 gal of beer. I usually average around 3.25-3.75 oz for 5-5.5 gal batches and am happy with my results. Looking in my notes for some past brews the most I ever used was 4.5 oz for a 6 gal batch. Also, keep in mind for lower gravity brews it is wise to not over do carbonation or the beer will have a "thin" taste and mouthfeel.