Sudden Acceleration

I just purchased a 1992 Toyota Camry in excellent condition bu I only encountered one problem. While driving the car it experienced a heavy acceleration as if I was stepping on the accelerator and not letting go. I tried stepping several times on the accelerator itself to see if the condition would stop but it did not. I eventually had to parke the car and open the hood where I then observed the throtle valve completely opened and had to manually bring it back to its position normal position and it then stopped the problem. I then stepped on the accelerator again and once again it did the same thing, the RPM's were almost off the chart since it was reving so high. The throttle body of the vehicle is new as it was replaced by the previous owner thinking this was the problem but obviously it was not. What can this be , any ideas? I kind of think that it might be the throttle cable getting stuck but just want to make sure. Thanks in advance for any assistance.