if it doesnt throw a code and the gearbox is playing up a ecu change to later model 2007+ ecu has fixed it in my previous exp
i had a customer who had rough changes after we did the box flush (no codes just did the flush for preventitive maintance) and it solved the problem
i used a ecu out of a 2007 gs300
if its giving you check VSC and codes etc its the gearbox solonoids