2500 RPM bucking

My axxess had a problem where it would not accelerate past 2500 RPM and would buck forward and back violently and sputter the engine if I tried to do so. Turning the key off then on again would usually resolve the issue. My speedometer also did not work which I though may be the cause.
This seems to be a somewhat common problem after researching.

example 1
example 2

The van is in 'limp mode' if it won't go past 2500 RPM, most likely and electrical component or sensor issue.

In my case the speedometer was also broken so that was a good place to start.
There are two components for the speedometer, the vehicle speed sensor (VSS) and the speedometer gauge itself.

The VSS is located on top of the transmission right about under the drivers feet. Access it from  below after jacking the car up and supporting with jackstands. Undo the single bolt and disconnect the single electrical connector then remove the VSS from the transmission. Some fluid may leak but it is not necessary to drain the fluid first.

Test the VSS with a voltmeter set to AC voltage and spin with your fingers. If you are getting voltage it is good. Using a drill to spin it is not recommended but will give you about 12 volts AC. Be sure not to use DC voltage on the meter as it will read zero.

You can also test this at the dashboard using the meter to measure AC voltage while driving. Test between connector terminals 15 and 21. I got about 4 volts at 30 MPH. The diagram below shows the connectors as seen from behind.

If the VSS is fine it's time to swap out some parts. It's hard to find an Axxess at a junkyard but the speedometer from a 90-92 Stanza will drop right in although the faceplate is different and you'll need to cut the Stanza faceplate with scissors to see the odometer. Below is the speedometer you are looking for from the Axxess.

And here is the Stanza speedometer in place. It does not say 130 like the Axxess and is green in color.

Replacing the speedometer fixed my 2500 RPM limp mode completely, and lets me check my speed as well.