Please let me preface this to state that I have been doing a great deal of research on my particular problem and I have not seen really anything about it in any great detail except "get it to a dealership."

Has noted above, 2007 STS 3.6L AWD with 78k on it. Bought it last year with 52k on it and been great right up till this past weekend when it developed a slight shudder when cruising level at and around 55-60 mph. Almost like driving over mild bumps in the road with no bumps. This is usually when the gas pedal is about an inch down (so barely maintaining it). Worst when going up a grade. Additionally, it picked up a hard shift at about 40 mph in what feels like a 3rd - 4th gear shift.

Car is at the dealership so no need for that recommendation and I was lucky that it is being worked on by a gm master mechanic. The issue is the torque converter and they will be replacing it.

Now, here is what I cannot fathom. How in the world does a torque converter fail at only 78k? I've owned and driven many cars, many different years in the last 30 years and never seen nor heard of one failing. I have a 68 Chrysler 300 convertible with a 440ci .030 over and I'm running that on the stock tranny and converter and have been known to have fun with it. The mileage is around 200k and still going strong. I just don't get it and I find it very frustrating.