My advice would be to stay away from the XUV, they have problems with the tailgate/rear window electrics. And not too many people know how to fix these.
I had a 2004 Envoy XL since 2007 (just sold it 2 months ago). I was very happy with it, not too many issues besides normal wear & tear things. Like was said, it all depends on how well or bad they are taken care of.
The Baby Bronco is going to take some getting used to for sure, the bells and whistles are endless. Do like the gas mileage compared to the Envoy XL (11 vs 24 in town). The 1.5L 3 cyl. engine is surprisingly peppy!
After many years of enjoying this site, helping me with my Envoy and hopefully me helping others, I have to say good bye. I have moved on to a Bronco Sport. Many thanks to all.
You might also check to make the intake air temperature sensor is working correctly. If the PCM (or ECU) sees incorrect air temps, it can affect the shift points.
Check this thread at GM Parts Online, item 16, liftgate reveal molding.
https://www.wholesalegmpartsonline.com/showAssembly.aspx?ukey_assembly=397182&ukey_make=1024&ukey_model=14546&modelYear=2004&ukey_category=19392&ukey_trimLevel=25306
One thing I can think of, maybe the front disconnect is not engaging from a stand still condition, but will engage while things are moving. The disconnect is known to be poorly lubricated.