[jhirasak]

Since you have indicated a lean surge in the rpm range of concern, I would recommend that you stepwise increase the richness of the idle circuit by incrementally decreasing the size of your idle jet holder. This might partially correct your problem. If it still exists after you have gotten to the smallest size of idle jet holder, I would look to add the 3rd progression hole.

Just as a point of reference, I had to decrease the size of my idle jet holder to 100 to get rid of an off idle driveablity problems. My idle jet size is currently 70.

John