The transmission is probably going into limp mode for some reason. Possibly completely unrelated to have the car on jack stands unless you knocked something loose.
The first thing to do is check your transmission fluid level and color. It should be completely full and the fluid should be a red color. Not pink, brown, black, etc.
You could then try making the transmission relearn the adaptive shifts by unhooking the battery for an hour or so. Then drive it really easy for the first 50 miles to allow the transmission to adapt the line pressures.
If all else fails, there is probably a trouble code stored in the PCM which will help pinpoint your issue.
