I too experienced a sudden drop in fuel economy and diminished acceleration in my 2010 FFH. It had about 120k miles on it when the symptoms started. I replaced the O2 sensor. That didn’t help. No ERG codes have shown up. Engine seems to run fine except for bad acceleration from dead stop and the diminished fuel economy. Given that I had been driving the car for 5 years at that point, I don’t think my knowledge of how to drive a hybrid has any bearing. Moreover, I’m very aware of seasonal fluctuations. I did have to disconnect and replace the battery. I can’t remember if my problems may have started around that time. Nor do I know what setting may need to be reset as a result. Any help is most appreciated.
