[blue62]

after you get your O2 sensors changed out.
Here is a way to test the SAI system to see if the air from the air pump is getting to the cat as it should.
With the Durametric hooked up and watching both pre cat O2 sensors.
Get the car warmed up and into closed loop.
Have the engine at idle.
Trigger the SAI pump so it is pumping air.
Your pre cat O2 sensors should go low in voltage.
Around .250 Mv or less.
Not exactly sure of the voltage but should go low and stay low as long as the air pump is running.
Here is why:
When you pump air into the exhaust the O2 sensors should see it and show a lean condition. (excess air). lean is low O2 sensor voltage. Rich is high O2 sensor voltage.

Another way to see if the air from the pump is getting into the exhaust.

With engine off run the air pump and see if you have air escaping at the tail pipe.
Don't know how well that works with pre and post cats.

I prefer to see O2 sensor voltage drop because that is what the DME/ECU is looking at when doing the SAI self test.

If neither of these tests work then air from your SAI pump is not getting into the exhaust.

So assuming you have no vacuum leaks.
Then the air pressure hose from the pump to the engine has a leak.
You have a bad combination valve (the one actuated by vacuum) or bad change over valve. (the electric triggered one) Or plugged air passages in the heads.

Hope this helps