Gas Pedal Vibration

2004 model peugeot partner 1.9D. I made a new rectification. there is vibration (tickling) in the accelerator pedal. did not exist before rectification. The flickering is not constant but it happens and does not happen. It happens more when giving gas and cutting. The pressure pad and timing belt set were also changed. this vibration (tickling) in the accelerator pedal can cause.

thanks.