Please post your code showing how you create an instance of this class, how you call doFind and how you're saving the return value of doFind.
I recommend using this.<class-property> instead of only <class-property> inside your class methods as it's clearer and will help you avoid accidentally creating additional global variables. findTask, findParams, esricMap, and results are all examples of this.
Just to be clear, are you using version 1.3 of the API for 3.1?