Mal, what base gasket are you using under the carb?
I ask this because the wrong base gasket can make the carb loose the idle circuit. Also if you have a lean condition caused by an intake manifold leak, the cylinder next to the cylinder with the intake intake leak will show that the plugs are different in color or inconsistent in color.

I have done a lot of testing with the MP single plane intake and T.Q. carbs and it is a very good match and works well. Your jet size on the primaries would normally be too big, David.