peugot speedfight 100cc?

ive got the thing tickin over thanks!i get a bit of white smoke when first starting,but goes well ( its been broken in now!)........except today i was going to work and was doing about 65 mph and easd off the throttle to start slowing down and it started screaming and rattleing (like a banshee!) then just died and lost all power as if i swicthed it off it did this 3 more times even when i was doing 30! what could the problem be as as now it dont want 2 go as quick as it did also my kick start is well stiff please help this thing is being hard work but it still starts