Hesitating to accelerate

Hello guys, i am facing issue from few weeks. Whenever i come to an stop or i start driving my 2000 4runner, as soon as put my foot a little down it feels like it disengaged the gear and then engage it, this continues till 45 or 50 kmph. And if i just get my foot off from brake paddle it start moving forward fine does show any problem. it only happens in first and 2nd gear. Can someone help me to find the solution Please...

 

Hard to tell what this could be but right off, have you checked the transmission fluid level and/or condition? Any OBD codes?

 

no code was showing related to transmission but was one for accelerator position sensor.

 

And now stop moving forward, but reverse is good. still didnt found any code.