[Rev]

That's the detent linkage. It causes a downshift when you floor rhe accelerator. It shouldn't have anything to do with the 2-3 upshift. I had a similar problem once. It was a stuck valve in the valve body. You can take that out yourself, disassemble , and check for the stuck valve. That's what I did and was able to free up the valve myself and restore proper shifting. I recommend getting the Ford shop manual if you attempt the fix yourself. You can do that without removing the trans from the car. Good luck on it. Any trans shop should be able to clean up the valve body for not too much $$$ I would think, but then they might also try to make you go for a complete rebuild.

Rev