found out the prob
thanks for the suggestion guys. finally found out wats the problem. it seems like the esc(an Xpress England 250HF. got it cheap for less than US$15 2nd hand) i was using was not set up and when i throttle all out, it seems to pass the limitation of the esc causing it to jerk. I using a cheapo tx that offers not much function. finally set the esc up last nite and the car was ready to roll.
cheers