I have the hesitation problem also. I had a 2007 MKX which accelerated quickly with no hesitation. When my 2 year lease expired, I turned it in and got a 2009 MKX. There is a huge difference in the acceleration - I wish I could get my 2007 back!! The 2009 hesitates whenever you need to accelerate - very frustrating.. It is very noticable when passing someone on the expressway or when expressway traffic is heavy with frequent breaking and acceleration - it is difficult to keep up with traffic because the car just doesn't accelerate smoothly. I haven't changed my driving style (except to be more cautious when needed) and my 2007 accelerated smoothly and perfectly which is why I don't believe this is "working as designed". I hope this gets addressed soon! I see there is a fix available for the 2010 models but the person who reported the fix also indicated it didn't fix their problem. Would love to hear if anyone hears there is a solution.
