87 Sammy, stock 1.3L.  Did a full tuneup, new o2 sensor installed last year.  Cat was replaced 2 years ago.

Readings at 15 and 25 mph:

CO2 measured 14.3 and 14.4
O2 measured 0.5 and 0.4
HC measured 7 and 3
CO measured 0.01 and 0.01
NO measured 2636 (gross polluter) and 2265 (fail)

A little background on this.  I went through hell gettin this thing to pass smog when I bought it in 09.  Finally found the cat was gutted, replaced it and it passed.  This last year, the carb took a crap on me and I ended up having to replace it.  I know it was running pretty rich for a little while, and I'm wondering if my new cat got ruined because of it.  Also, the engine does burn some oil......i'm sure it needs rings. 

My question is, would the numbers above indicate the cat is bad?  If not, what else would cause such high NoX readings?  All of the other reading are well below the California limits.

NOX is formed from high burn temps, clean/replace the EGR and
try again, that is the biggest contributor to NOX

If that doesn't work you could get rid of the gas and replace with E85,
that burns slower and leaner and might pass your truck if all else fails

Does anyone have a link to how to properly clean the egr system on a sammy?  I could only find a link to the x-90 on acks.

Just went out to clean the egr, and found dark black oil dripping from the egr valve.  I have another egr valve i can put on it, but is there something else I should be looking at as a cause of this or is it just a matter of the diaphram going bad?

Changed the egr, it almost passed but not quite.  Squeeked by on the 25 mph test (1273, 1282 allowed) but failed at the 15 (1821, 1166 allowed).

Drove over and had the cat replaced again.  Nox readings at 15 mph: 174.  At 25 mph: 477.  Passed with ease.

If you  drive off road much especially washboards, it will destroy a cat. Or running rich for a while.