[Yorkie]

I think your carbs need an overhaul. High idle when warm tends to be an air leak past the throttle butterfly shafts. Often the bushes are worn and as I recall there are seals present on the ends that need replacing. The throttle response might be the pistons in the dash pots not moving smoothly. Recommend that you remove them to check for smooth motion and also check the oil and seal in the plunger. Light oil is necessary for the pistons to move smoothly. The o-ring also typically needs to be replaced. The SUs are great carbs if in good condition and properly set up.