please help me to find a solution for this problem,
every day in the morning when the operator starts the forklift and starts to accelerate the forklift by pressing the pedal , the forklift starts to jerks in both directions( forward & reverse) and this continues for around 45 minutes and after that the forklift moves in a normal,smooth operation for the rest of the day. moreover there is no error on the display which may indecaites for any fault inside the forklift.
next day, same problem happens with the same steps as descriped above.

we have made some checks for the battery connections ,replaced the traction motor sensors,replaced the accelerator pedal sensor and cleaned all the electrical sockets.

please help me with this problem and try to think if the problem may be caused due to a mechanical problem or no ?