Transmission hard shifting and shutter

Hey there, new on here and just got a 2nd gen Tacoma with 300k miles. Shifting sometimes hits hard and at 35-40mph there’s a bumpy shutter feeling. I’ve read that the fluid, filter, and additive would help. Any suggestions much appreciated! Btw there are other noises/ issues but this seemed the most important. Thanx!

 

Does it still do it if you drive in 4th? If not it’s the torque converter, the fluid exchange and additive may help but it will come back.

 

Need to pull a transmission code...Hard shifting could indicate a few things and with 300k you got great work out of the trans,,

 

Will any scanner pull transmission codes?

 

I’ll try to drive in 4th. When going from park to drive it sometimes hits hard.

 

Not all scanners will check for tranny codes...Check autozone, etc see if their scanners will...But you do need to see what codes you may have.