try ko kaya palitan yung buong carb kasi malamang may somewhere dun sa carb eh. may tinakpan na dati dun yung mechanic pero bumalik nanaman yung sira. alam ko puwede i convert yung carb to EFI eh. para d na mag engine swap. try mo pihitin yung pin na nasa likod ng carb mo, see if that will make any difference. Hindi ba pumuputok yung muffler mo when u let go of the gas while the car is moving?