Did some hater sabotage you?
I've seen that happen more than once to cars at shows, I have taken action on one of them punks also after the show in the dark on his way home after seeing him do that to a another racer
I told the racer what I saw and told him to not start the his car with out taking the carb and intake manifold off to remove what that punk drop down the carb when he thought no one was looking
I never saw that jerk around cars again at the races or any of the local car shows or gathering
Actions speak louder than words