2006 Toyota Tacoma Prerunner Automatic

My 2006 Tacoma has intermittently been dropping a gear when I slow to a stop and then try to move forward, or when I start the engine and put it in Drive. Twice it has dropped into Park after moving forward a short distance. I can resolve the issue by putting it in Reverse and then back in Drive. Taken to dealer twice but they can’t find a problem, since the check engine light does not come on and there are no codes. Any ideas on what the problem is or what I should do next?

 

Has the fluid level been checked?

Is it literally going it to park?
Or "neutral"?

Dropping into Park would be bad. Really bad. The parking pawl would be taking a beating.
BANG.....

 

I'd be checking the shifter cable linkage, all along its mounting points.

We've seen the cable bracket that mounts to the under body rip out and cause issues.

Heck I think I helped someone on here find that issue once. Lemme see.

Hmmm one 3rd gen with that issue https://www.tacomaworld.com/threads/shifter-cable-rubbing-on-tcase.790031/