Problem with acceleration after slowing down.

Starting in 2011, there is a brake override system in place which, if the brake is depressed the least amount, the engine will not rise above idle. This hesitation problem is very common for 2 footed drivers. If this is the case, ensure that your left foot is completely off the pedal before hitting the gas. If not, have the override switch on the pedal checked for binding or bad adjustment.

Yes, this happens to me a lot with my 2011 Sonata. Very dangerous and unsafe - and I drive with only my right foot.