I have a 89 sc 5 speed and its fine when you go from a stop but if your on the highway and you go to speed up not downshift or anything it bucks I have no check engine light Im thinking it may be plug wires I just changed the plugs and it only does it if I stomp on when accelerating if I ease into its just fune and also brand new fuel pump 190lph maybe I should change the fuel filter any help is greatly appreciated Thanks Justin