Do I need a new transmission?

Hey guys, first post here so apologies if this is posted in the wrong place. Anyways, I have a 2006 4.0 double cab prerunner with the 5 speed auto with 267,000 miles. I recently drove it down from Salt Lake UT to LA and the trip was uneventful. However while driving in LA, I hit the gas and then the truck would barley accelerate for 5 seconds like a clutch slipping on a manual before seeming to “grip up” and the truck pulls real hard and rips through the gears. This is not a steep incline thing as it was happening on flats and even slight downhills like when I was getting onto the onramp on the freeway. However, it also would not go into 5th gear and hovered around 3k rpm in 4th gear. While this was happening I herd multiple loud clanking sounds seeming to come from the transmission. ( the truck not wanting to shift into 5th has happened multiple times in the past but none of the other aforementioned symptoms occurred) I thought I definitely need a new transmission but when I went to drive it today, none of the problems mentioned above were present and it seemed to be perfectly fine. I have to make the 600 mile trip back and I’m worried it’s going to act up leaving me stranded with an expensive tow bill. Any ideas on what i should do? I’ll gladly put in a used transmission, but want to make sure it is in-fact a transmission problem that would warrant replacing the whole thing. The drive shaft also snapped about 1,000 miles ago and I had it rebuilt with zero issues since. Sorry for the long read, just want to be clear on what is going on.

 

Quick: when its hot pull the fill plug on side (not the drain) and see if its low (insert finger if none comes out) and add till its full.
Or get the dealer or a shop to do a full exchange of all fluid as about 3 in pan and 10 in converter.
Many on TW don't like the full exchange and many do. I had dealer do it and shifted better and stronger 5th gear torque converter lockup.
There are some internals that can get gummed up but I would try above first as quick and easy. Full exchange was low 200s but probably went up as everything did.

 

^ Have a professional check the problem (along with the fluid level).

 

That's not the procedure to check the fluid level, for the proper fluid check see the thread below but note the check temperature was changed from what the thread states to 95-115F.
But I do agree the first thing is to check the transmission fluid level and condition.

https://www.tacomaworld.com/threads/how-to-drain-refill-automatic-transmission.63851/

 

If you need a transmission (A750E) I have one that I’m ok to let go for cheap. Dm me any questions. It was pulled from my truck fully functional.