Trans shifting feels wrong

Got a 2009 DLCB running 265/70r17 BFG KO2 tires and a 3" toytec lift. I feel like my trans shifts weird now. It's like as a slow down below 30mph the trans shifts up and down more than I would think it should.

I was going to check the trans fluid level but after reading it looks like it's a closed system and you can check it?!? Is that correct? How do you make sure you have the correct level of fluid?

Any other items I could check as to why it feel this way

Thanks
Bv

 

Correct there is no Dip Stick.

It’s a bit of a PITA to check correctly.
Here is a link you can look at and see if you are up to checking your self.
https://www.tacomaworld.com/threads/how-to-drain-refill-automatic-transmission.63851/

 

I find that if my truck continuously shifts below 45 MPh. (Usually on back roads with a lot of hills)
I shift to 4th and drive it that way.
Your tires are likely not helping your shift points.
You maybe overthinking it some after the lift and tires.
Drive it awhile and see if you and the truck adjust.

 

I do the same thing. My commute is mostly city (6.5mi). If you keep it in 4th it will hold the gears longer. I only shift back to 5th after I hit the 50mph stretch.

 

Have you serviced the slip yoke on the driveshaft? Try that first. As my 15 was doing strange shifting until I lubed it.