Yep, that could be the case Jeff and the most common sign of a dieing engine is a sudden jump in performance (but uncontrolable), so I wonder if they had the little 18 running on 30%? Well anyway the stretched rod would have increased your compression, advancing your timing and maybe this actually put your motor into it's optimum timing for the fuel you have ??? But if that is the case then I suggest removing a 0.1mm shim from the head, fit a new rod and see how it likes that.