Any Transmission experts out there ?shudder issue

I'm having a problem .shudder between 25-45mph.and the transmission seem like it shifting to early .wants to go to over drive to early it seems .it won't do any of this and drives very nice if I put the gear selector to 4th.and also no shudder in Drive if I accelerate above 2500 rpm
It's been doing it since I bought it 2 years ago and hasn't got worse

All recalls up to date
-leaf spring
-driveshaft and carrier bearing
-frame

Trans has had Fluid change but not a flush .but don't know if all oil was change or just pan

Thinking of bringing into dealer for trans Ecm reflash (tsb 0393-09)?????

 

https://www.tacomaworld.com/search/10062325/?q=shudder&o=date&c[title_only]=1&c[node]=5

 

I got the same thing in my 2013 i just bought....did a drain and fill and put 2 of the lubegaurd shutter fix in it... did not do anything!!! Still got it on take off and 30 to 45mph......ima try a flush at the dealer then add lubegaurd cuz a dealer willnot put it in for you....bet $1000 it needs a converter.

 

Have you seen this post.
Maybe it will help you?
https://www.tacomaworld.com/threads...th-pics-for-second-gen-4-liter-trucks.289913/