Hi Brian,
I saw cats online for 80 bucks, I would change that out if my ideas below don't work.
I didn't pass CA smog the first time as well. I found that the cylinder head temp. sensor was fried and giving bogus feedback to ECU based on ECU fault code and measurement with a multimeter.
Look for fault codes on the ECU. I just ripped off the plastic cover from the ECU under the seat. Flip the switch from normal position till the lights flash 3 times together, then flip back to normal position. If all is well you will get 5 red then 5 green flashes. If you get any other combination there could be a problem. I think the temp. sensor was 1 red 1 green, but forgot at this point.
Based on the factory manual, the inputs for mixture control include the cylinder head temp. sensor.. I found that when the temp. sensor was malfunctioning the ECU never would get into closed loop mode (i.e. never used the o2 sensor to control mixture) proved by putting the ECU into mixture ratio diag. mode.
The temp. senor I am talking about is buried under the distributor, not the coolent temp. sensor on top of intake. It is a MF bastard to get to. I am talking about the V6 here as well, but the 4 cylinder works on the same concept. Invest in the factory manual if you have not already. Don't mean to preach if you know this already.
Long story short is I disconected the temp. harness and put in a $1 300 ohm resistor and the sucker passed the 2nd smog try.. it was close though. I have the auto and I made the guy keep the tranny in power mode to keep the revs up. I am confident that a new cat would have helped the old beast easily.
Bottom line is mixture control is key, make sure all inputs are working correctly.
Maybe check the EGR solenoid, too. I think the main component of failure is ECU malfunction due to bad inputs.
Hope this helps.