Vacuum operated secondary butterflies.
Figure 4
Click Figure 4 in this Autozone link
And yes, you should also test for a blocked precat. Unplug the upper Bank 2 O2 sensor. If the car performs better, it could be the Bank2 O2 sensor. If it doesn't improve, then try Bank 1. Don't know how to test for the 95 main cat (without removing the cat or flexible pipe) other then sending to a shop.
Whatever happened to the PS Steering switch? Did that not turn out to be the/an issue?
