Slams into gear but its an intermittent problem

Hello,

Anytime there is a shifting issue the first item needs to be checked is the transmission fluid. Low or contaminated fluid can impact the way the vehicle shifts as the fluid might not circulate properly creating shifting issues.
Make sure the fluid is at the correct level and in good condition.

Many times, changing out the filter and fluid can vastly improve the shift quality of these transmissions.

https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

This can also be due to a failing transmission shift solenoid or a weak transmission oil pump.

Good first step would be to do the fluid and filter change if it has not been done in a while.

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.