My T2 runs RICH, with bigger primary and secondary injectors. Does that mean I'm building a lot of carbon in my engine? Should I be doing the ATF trick often? Is that the best way to get rid of carbon buildup?

 

As far as the carbon build up goes, if your car is running rich your engine will tend to build up more carbon on the intakes....
I have seen some one on the forum actually filled atf all the way to the top of lower intake!!!!
Remember the longer you let the atf sit the better it works!!!!