My Toilet Overflows

I made a previous post about this, but now I have somewhat of a different problem. When I try to flush the toilet, the water doesn't stop flowing to the point of overflow. I shut off the shut-off valve before it actually overflowed, but now the tank's water level receded. I tried plunging the bowl, but it hasn't yielded success. I'm wondering if pouring water into the bowl will help get the water level in the bowl to its correct level. Should I do that, or should I do something else?