Help! What the hell could have happened?

[CELA]

alright, so i've been looking online for all of the things that could have gone wrong. And I am still confused.
First time I smogged I passed everything except for the NO at 15mph.
As seen here:
http://i956.photobucket.com/albums/ae46/steez_17/1stCropped.jpg
So I get my car diagnosed at a different place cause it was cheaper, tells me that the theres a slow response from o2 sensor and poor efficiency from catalytic converter. So I try to save some cash and just swap the o2 sensor first maybe i wont have to put up the cash for the cat.
I change the o2 sensor, and reset my ecu, (but i was told that i didn't let it sit idle for long enough.)
As I drive the check engine light stays on, but eventually disappears. When I get some free time I head to the smog station, the light turns on again, and then goes away before I get there. I get tested, and the results are worse than before!
here they are:
http://i956.photobucket.com/albums/ae46/steez_17/2ndCropped.jpg
The only thing I changed was the o2 sensor? Could the cat have gone that bad that quick? I'm thinking maybe I didn't reset correctly? Any advice appreciated

[s13silvia123]

change your motor oil. you just barely passed so just change your motor oil it helps by alot as well

[drift freaq]

have you checked all your vacuum lines to make sure none are leaking? I would suggest you clean out your AIV system. The simplest way to do that is to remove the intake tube right at the throttle body and while the engine is running you rev it and spray carb cleaner directly in. It will put out a ton of smoke out your tailpipe as it cleans the system. You should also heat your cat up before putting it on the dyno. That means running it a 2800 rpm for at least ten minutes.

If your cat is actually on the weak side you might have to replace it. Oh and putting in fresh spark plugs and cap and rotor help as well.
If you do all these things you should be able to pass. I have taken gross polluters and done this stuff and made them pass.

[CELA]

What could have caused the numbers to bump up that much for the second test? I mean all I did was change the o2 sensor.