PIAGGIO NRG EXTREME?

HI GUYS I HAVE PROBLEM. I RODE MY SCOOTER FOR ABOUT 25 MILES AND HAD TO STOP 3 TIME NOW WHAT WAS HAPPENING IS I WAS RIDING ALONG AT ABOUT 50 MPH FULL THROTTLE AND THEN THE REVS JUST DIE TO ABOUT 4000 RPM AND I SLOW TO A STOP BUT ENGINE KEPT ON RUNNING (NOW SOMETIME THE ENGINE DOES CUT OUT AT THE LIGHTS IF THIS HELPS)I TURN THE ENGINE OFF FOR ABOUT 5 MIN THEN START IT AGAIN AND IT SLOWLY REVS UP TO THE REQUIRED REVS TO MAKE THE SCOOTER GO.

PLEASE HELP MANY THANKS