I have an 85 tomos golden bullet with a problem. When I start it up it runs really sluggish, and eventually stalls out. But heres the kicker: Every once in a while, I start it up and it runs like a top! It runs beautifully, but after 10-20 minutes of riding it gets sluggish again. If I turn it off, and back on it's sluggish. Now when I say sluggish, I mean it stutters, has very little torque, coughs out sputters of black smoke, hesitates, and eventually stalls. But why does it run perfectly sometimes? I don't get it!!!!!