50cc GY6 Surging

I recently got a scooter with a 50cc GY6. From a stop, when I go to apply power, it only allows me to go to half throttle before nearly dying. I can pulsate the throttle to get it up to speed, but when cruising, the motor surges. Rarely, it’ll have a few seconds of running perfectly, then go back to bogging down and surging.

Carb has been cleaned New spark plug

Any ideas where to start looking? TIA, I’m new to all of this and still learning!