Dear Sajid,
I had a similar to your problem even nissan sunny is 2008 Model went to Acceleraor Pedal Sensor Failure caused sudden and unable to raise the speed while i was driving on 04-10-2011. Finally i scan to find the problem which is best way to find and solve the issue. New APS sensor been replaced that cost me around 1150SR (13500 Rs). So Better Scan your engine by computer enabled and sovle it.
Thanks