I recently bought a 200k miles 05 ls340
and a couple days ago my transmission started to act up.
- engine light
- VSC light
- stuck at forth gear
- P0766 Shift Solenoid D performance/stuck off
1st mechanic [20+ years fixing Japanese cars] says to replace the transmission
2nd mechanic [ASE] (im taking it to him tomorrow)
3rd mechanic [AAMCO]

What do you suggest I do

When I Test drove the car b4 buying, the brakes were acting up when i was gently stepping on the brakes. Then it would jerk out of nowhere. Then go back to normal.
Seller then brought the car to his "mechanic" and changed the motor mounts and suspensions

Then when I started to drive it, after like an hour the code started to appear

Reading the forums, i found something that is related to the brakes. Could it just be a ECM issue?

 

have you ruled out the very common ECU repair issue ?

 

I am not mechanically inclined. Do you suggest i take it to my dealership?