I have a Saito 80, OS F plug using Performance Plus 15% fuel, APC 13-8. The engine has about 3/4 gallon through it. When the top end is adjusted properly (3 or 4 clicks rich) the idle must be richened considerably in order for mid-range to not be lean. When idling this rich it will run for15 seconds or so then die rich. In this state the idle must be set high enough so that I have to chase it around on the ground. If the idle is leaned so as to idle properly, the mid range is lean. Another fellow in our club has the identical problem with his Saito 80 and has been wrestling with it for a year with no solution. Any thoughts?