Why wont my moped stay on?

Why wont my moped stay on?

When i start my moped (if it starts) then immediately bogs down and dies. Or sometimes it starts and if i give it gas at all it will die. If it starts and i leave it on the kickstand and don’t touch anything it will rev itself basically and the back tire starts spinning faster and faster but if i hit the gas it just dies. I have no idea whats wrong with it and no idea where to start. Please help.