If he was eating live rats before, I would stick with live for a little while (a few feedings - get him on a schedule) and then you could try to switch to F/T. Moving to a new "home" is pretty stressful, I wouldn't recommend changing the type of food he is eating too at the moment. How long have you had him? Did he get at least a week to "settle" in to his new surroundings? What is his setup like? Temps? Humidity? How are you measuring temps & humidity?
Also, I would not recommend handling him (other than for cleaning) until he is eating regularly for you.
I'm sure someone with RTB knowledge will chime in soon
*EDIT* Just realized you did mention you have had him 2 weeks.