I have a 1980 xs1100 yahama , the carbs were rebuilt and synced , so air gas mixture is good to ! But it runs fine when idle is a little higher by twisting the throttle ....but if I stop at a light and let the throttle sit normally the idle goes lower and lower then dies ! It started up fine right away after it dies but it’s a pain My machanic can’t figure it out but he has tried switching the MDI box and ignition coils to no a avail , he thinks it’s the ignition ....you guys maybe have heard of this issue ? And what fixes it ????