I do not think it is the steering rate as he just about ruled it out with what he and I are talking about. But just in case do you know what the steering rate is and how to change it on the TX I am guessing it has one. Sorry I know very little about Traxxas.

Being the stock RTR servos are not very good now would be a good time to up date to something better.

Sorry if I had it in front of me I could tell you quickly as I have many servos and I could hook one up to see if that was the problem.

How old is the vehicle as it might be covered under warranty?