'17 LT CCSB, 97k. No warning signs of trouble, went to leave work Thursday and it just revved up and would barely go like it jumped out of gear. once it idled down little it felt like I was getting rear ended repeatedly. No warnings on dash. Turned it off and contemplated life. Buddy came back to work to pick me, tried it once more and it kinda repeated then proceeded to run like normal. Dropped it off at mechanics house to look at, he test drove the next morning and of course, could not replicate. Stayed home mostly over the holiday weekend, on Monday I did the fluid/filter change, was immediately worse until it got warm. Drove yesterday to work, only problem seemed to be a delay going in to 1st after shifting to drive. Same when I left home this morning. Drove 4 miles and had to stop at top of a hill, acted like it was in neutral. Shifted to low and selected 2nd gear, it wasn't happy about it but then drove normal. Made it about 16 miles before I had to do some stop and go, still no 1st gear. Taking off in 2nd, shifted to 3rd and 4th, then that's where it stayed.wouldn't up or down shift. 40mph all the way to the mechanics house where it will sit until I find a dang transmission I guess.