My 2011 Ford Fusion Hybrid also had some significant lag when accelerating from stopped, I also noticed a drop in mpg’s. I found an April 2020 Ford TSB for the 2010-2012 Ford Fusion Hybrid/Mercury Milan - Ford TSB #TSB 20-2142. This calls for reprogramming the battery energy control module (becm) and the power control module (pcm). I was hoping this would help the mpg. I thought the acceleration lag was due to a throttle body issue (it was cleaned but didn’t significantly help) but after having the reprogramming done, our Fusion’s acceleration lag & mpg have improved. The reprogramming cost $140. If you’re going to have this done, take the TSB # with you, the dealership had a hard time finding the info on this.
