Yup ,it's definitly time to see if the primary 02 sensor is fouled. Now what do we think would cause the primary to foul? High EGT from running to lean? Carbon buildup from running too rich?

If the primary appears fouled, I wonder if it would be worth your time to hit the secondary with some compressed air, and try it in the primary location. Maybe it's a little less fouled.

If you're fouling O2's sounds like you may need some tuning. AFC? Or the hondata s100b is cheap, except for the tuning costs. And maybe you should post your setup, including fuel managment on one of the forced induction forums. See if you can do fuel delivery better.

-PHiZ