After a couple hundred miles on the new manifold, I'm happy to report performance has improved. The improvement comes from smoother power, smoother shifts, likely from cleaning the fuel injectors, although it's possible the bad intake manifold may have also had an effect on performance. The care drives like it's new, which it should after only 45,000 miles. It's a subtle change.
I'm curious to find out tech tip 24-09-02, if anyone has access to the database.