hey guys,

my 2000 civic si seems to bog violently, randomly , downlow, right after i shift, (sometimes to the point where the motor just shuts off). Furthermore, randomly, my vtec would feel extremely weak. Although I hear the vtec crossover, it pulls like an ex. The must frustrating thing about this problem is that it occurs randomly. I had the car checked out twice at a shop and they could not find the problem because it simply was not happening when they took it out for a drive. I do notice these problems after driving aggressively however. I had the grounding wires resurfaced, fuel filter, spark plugs and wires, dist. cap and rotor replaced. same thing happens... anybody here have any ideas??

thanks in advance