I have a 2014 impala lt with the 4 cylinder and recently been having issues when I get on the throttle. It’s perfectly fine until it hits about 4500 rpm then it just sticks there and won’t even shift. It will shift if I let off a bit and let the rpms drop a bit. It’s recently started happening and I don’t even have a clue why it would be. She is a highway destroyer so she has about 165,000 miles on her and nothing has ever been replaced. Any ideas?