Smog help!! 93 240sx stock

[darkslide92]

Okay so I know there's a bunch of posts about this already, but most are pretty old, and maybe someone might have other ideas than I've read.*
The car: it's an all stock 1993 240sx. Has new egr and timing was adjusted back to stock (was previously retarded to help lower NO's). Exhaust is fully stock except for the fact that previous owner put two cats on the car to help pass. But i later found out it doesn't help so I'm planning on changing out to a stock downpipe.
Readings: smog tech said they were very strange lol. Measured HC at 10ppm for 15mph and 4ppm at 25mph (avg is 43@15mph & 26@25mph). CO's were both measured at 0%
Now the fun one. NO ppm max: 493@ 15mph & 516@ 25mph. Avg is in the mid to high 100's. But mine measured 1550 at 15mph and 171 at 25mph.
Thanks in advance for any help and ideas