My 2012 challenger SXT with around 118,000 miles on it. When I get to around 1500 RPM and stay at a steady speed the car has a shake too it. Then it feels as if it has trouble shifting into the next gear then when it finally switches gears its a hard shift. Also when stopped at stoplights the car shakes and makes a creaking noise like the brakes are not fully applied even though they are. Obviously the hard shifts are from the transmission but does anyone know what any of the other issues could be from. Ive taken it to the shop and they said they did not feel any shaking when driving it, but it does it a good amount around 1500 RPM. Thanks in advance.