Help me diagnose this transmission issue
 

2008 Cayenne base which is new to me. I got it with 112,000 miles, put an extra 3,000 miles on it. Here is the issue: the gear shifting is is very rough when it upshifts with no load, in slow moving traffic. It feels like shifting without using the clutch, if it was a manual transmission. I am thinking it may be caused by some drive shaft issue. My other hypothesis is the ATF needs to be changed. Which is it? Has anyone else experienced something similar? The issue only occurs wilth little or no load on the transmission, in eco mode. No problem in sport mode.

Could just need to be re-adapted. The adaptation will need to be cleared with a scan tool, then the adaptation procedure carried out. Also when performing the reset make sure there are no fault codes. I seem to remember a bulletin for fluid wicking in to the harness and causing all sorts of issues. Tiptronic Fault code 1314 is the one I remember but that was a long time ago! You can unplug the electrical harness from the back of the transmission and look for fluid...if it is wet inside the plug that is probably your problem.

might be ready for a valve body redo

Valve body is a good guess too if there are no faults in the Tiptronic module.

Thank you for the valve body tip. I read it mostly affects 4-5-6 shifts which is my case, so very possible.