I have had sensor cables that would work then not work depending how it wiggled if it was freyed or loose pins going into the plug. If its doing it though 3 or 4 minutes into a run every time sure sounds like a heat issue to me be it the motor or at some point in the esc. Never had a viper esc apart but a cold solder joint or a plug inside of it thats loose/bad connection internally or externally get hot.