NEED HELP!!

[skyyred]

I need help i dont know wats wrong with my engine..i have a 92 240sx with a red top sr20det...ive had if for a few months now and everything was perfect on it...recently as i was speeding up to get on the freeway... i gunned it in third gear and around 5500rpm the motor started bucking and making a wierd rattling sound(i didnt see any some or anything)..every time i gun it it starts to do the same thing..im guessing it might have to do with the turbo ...not sure though-the car runs fine at low speeds-it idles fine the problem starts when i gun it... i can speed up slowly

does anyone have an idea of wat might be wrong..