Continual throttle body problem

Purchased this car in 2014. About a 1 1/2 years later, I was driving it and the check engine light came on and the light with a car with two squiggly lines underneath it (sorry can't remember what that's for) then I lost most of the power. Took it to a Nissan dealership, was told it was the throttle assembly and replaced it. Three months later it happened again. Back to dealership, told it was the throttle body. Replaced it. Three months later, it happened again so they replaced both of them. Again, it happened. Took it to a new dealership the next day and was told they couldn't find anything wrong that the code was a past code. Any idea what could be going on? Anyone else had this problem?