It is very difficult to determine these faults on modern motors,has it been on a good code reader? I don't like guessing as it can cost a fortune nowadays, have had other models like this where it was a faulty throttle pedal but with electronics who knows,if at all possible it may be worth going to a good scrappy for a used unit,if he is a decent and reputable guy he should let you try it and return if that isn't your problem,good luck.
cdc
January 2014