Ok..
If the 02 is new and the pump is coming on with ECU demand, then the problem is that the air valve between the pump and the head exhaust ports is not opening. That is what he SOV does , it allows engine vac to pass on to the AIR valve when the pump comes on.. and that air valve allows the air from the pump to go into the exhaust ports of the head and cause a lean condition at 02 , verifying system OK....so you want to look at that valve, the vac line going from the SOV to it, and also check that the SOV does open when 12v is applied. The SOV is mounted in tandem with th EGR SOV.

I have also seen situation where guys have mistakenly switched the wires on the EGR/AIR SOV connectors b/cx they are right next to one another and that will give you the same fault. [ although usually also with a code 5/egr]
Those would be my next diagnostic steps..............

If you have the CD , go top Emmissions and look at vac schematic and you will see the entire AIR/SOV/Vale/ and check valve routing layout.