[Mr. Lim]

if (p3_sw_trig==1)
{
   pwm07=175;
   pwm08=175;
}
else if (p3_sw_top==1)
{
   pwm07=90;
   pwm08=90;
}
else
{
   pwm07=127;
   pwm08=127;
}

try this... just beware if you push both the trigger and top button at the same time, it'll still go forward.