What do you mean, 1/16th from recommended settings?
If the engine idles fine, but fails to respond well to throttle application, idle is too lean. Open up 1/16th turn at a time, until trottle response is ok, even after prolonged idle. In between, always reset the main needle to max rpm, and open up the main needle to the point that the engine just starts to loose rpm. Remember: Main needle and idle needle work together to provide full bore mixture. Final tuning of the high end is to be done by judging the spark plug. The central electrode isolator should be a doe tan, or light gray, depending on oil and gas used.
The walbro carbs do not have the usual acceleration pump that automotive engine carbs have, so try to resist the urge to quickly jam the throttle fully open. Instead, <apply> throttle in a way that the engine can follow. It is a relatively fast sweeping stick motion, just like operating the accelerating pedal in your car, which allows the carb internal fuel flow to pick up speed while you apply the throttle. Some transmitters have the option to reduce servo speed. Use it if available, or use a rather slow servo instead for throttle. The prop needs to spin up as well.
Resist the urge to lubricate too little. Follow the manufacturers recommendations. Some synthetic oils cannot be mixed below 1:50, I like 1:35, so I will not use these oils. (I use Mobil 1 2T racing or Valvoline Synpower)
Plug fouling stems from wrong carb adjustments or wrong plug type, not oil content. Too little oil will cause the engine to run slower and wear faster.
Good luck.