Trans is in limp mode,
Go to an Autozone, Advance, or O'reilys for a scan. Limp home means engine problems too.
Overheating is a problem or loss of signal from an engine sensor. One thing you might try is after, and only after you get a scan is to wipe the memory.
The companion computer may have embedded info and is responding to the old "Limp signal".
Check any Vacuum lines or Vacuum dashpots which can affect powertrain controls.
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