more than likely just the TPS, does the stepper motor twitch and whir and click when you turn on ignition, if it does more than likely it is fine, also I know one of our Sydney based owners had his TPS replaced by a dealer and they did not do the ISCV adjustment, this syncs the TPS and Stepper Motor for it to all work in harmony with each other do you have TuneECU, if so you can do it your self, it does need to be spot on as I found wile experimenting with altering the sync settings of them