The carb has an O-ring seal. If you remove the carb you’d see what I was talking about. Sometimes they leak, which is bad. You said you saw fuel coming from around it….that is bad.

But.

If your servo was surging along with the rest of it, you also have an electrical problem my friend. It could be the radio, the receiver, the batteries, or the servo itself. When you pull the trigger on the radio, the throttle servo should go and stay plain and simple. I'll try and help you diagnose your problem as you check things and report back.