Thanks to Danny, Gordon and drclock for advice which solved my carb linkage problem. I was having the drivers side carb fail to return to idle 90% of the time. This caused the carbs to be out of synch at idle and I was getting popping sand some backfiring.
I was having binding in my linkage that caused the trouble and was surprised to see the amount of wear the balls that ride on a spring inside the end of the hex bar. The wear you see was after only about 20,000 miles on this linkage.
I hope the picture is clear enpough to show that half the metal is worn off on the left one---the one on the right is how a new one looks.
In replacing these parts I also saw that the Heim joints were stiff and not able to swivel as new ones do. This stiffness led to the overall binding of the linkage. Also to my surpriose, the spring that goes inside the hex bar ends was totally missing on the passenger side! I am still wondering why that was missing but I have an idea.
New balls and heims gave me a linkage that is smooth as butter with both carbs closing solidly 100% of the time---no out of synch condx and a happy owner. If your linkage is sluggish take Danny's Alan's and Gordon's advice and look for worn components including stiff Heims.