check engine light on, on acceleration hard shift then limp mode came back to normal got home has no reverse checked for codes =pressure valve stuck car stuck in lower 3gears. at 60mph would upshift normal under 30mph, to to Chevy house checked it out solution = new transmission they want to pay 1600 toward fix and me pay 3600. its out of time warranty 5 months but way under on mileage told them had sit for about 8 months while I was recuperating, not happy with this at all. could see me pay for10 or 20 percent but not that amount ,and they want old transmission cause they say is warranty, I think they are hiding the issue as I was a mechanic for over 45 years . worked for a GMC ,Pontiac dealer, large trucks and equipment for Halliburton spent 16 years working on Caterpillar Waukesha engines worth over 1.5 million a piece so no dumb .reads about hard shifts on impalas seeks to be issue here but Chevy doesn't want to stand by it,100% any other ideas or help welcome open to new ideas on handling this expensive issue?

First complaint at 18500 miles. Transmission shifts hard (jolts) while negotiating stop-and-go traffic between 15 to 50 mph, especially on the freeways. Dealer declared it a fuel injection issue and recommended that service for $280, which did nothing to fix this transmission issue.

My second complaint to the dealer for hard & delayed shifting issue I complained about several months earlier. Dealer claimed to have performed a reprogram, but I did not experience any improvement. Problem persisted.