[Haskell-beginners] slightly scramble list randomly

I want to take a list of size N that starts in ascending order and "slightly randomly scramble it"--- each element is moved within M steps of its original position (there can be some tolerance for slightly over M). The application is a backtracking algorithm that produces random solutions but tends to favor certain choices--at each node of the search tree I can evaluate the goodness of each possible next step, but I don't want the algorithm to always take the best choice. Just roughly, much of the time. Dennis