Unburned fuel draining out of the lower unit is normal. This is not a fuel efficient engine and there's lots of unused fuel that drains out when you tilt the motor or pull it out of the water especially if you idle around before stopping the engine.
Why too little speed? Could be a lot of things from a dirty carb, plugged high speed orifice, carb & ignition not linked and sync'd, low compression, bad gas, heavy boat, dirty hull, anchor still down......need more information.