Keith my first thought before reading your post was 'Ethanol' but you are running pure gasoline and driving the car regularly so it's not sitting a lot, sure looks like old gas/water contamination but that must not be the case.
Years ago a friend with a Chevy Blazer running Ethanol when it first reared it's ugly head had the same gooey white junk in his carburetor.
Interesting. I'm anxious to see what others say
