I keep failing emissions. I installed a new cat and a new 02, and i still fail with high numbers. I failed the hc and the CO test but passed the NOx test.

 

Replace plugs and wires, do all tuneup stuff. Replace air filter, fuel filter. Make sure BAC valve is working properly, as well as ACV.

 

Set the TPS according to the 1V method and/or 1 light method as described In the Manual. Atleast for the latter It's described In the Manual.

Whats the condition of your Air Control Valve? You could take the vac hose just above the ACV (front hose), block off that hose with a screw. What that does is relaxes a diaphram and sends air thru the Split Air Pipe all the time to the Cat, where as if it was left as factory, it sends split air to the cat only when you let off the throttle.

 

Check the Air Control Valve. My 85 GSLSE's hydrocarbons were 1200!!!!!!!! I bought a used Air Control Valve from Rex Foreign in Gardena (all Mazda Junkyard) and my Hydrocarbons dropped to 120. I only went to rex because its kinda hard to find a gslse at the pick a part or ecology yards. Non turbo second gen should be no problem to find at the local wrecking yard. The workshop manuals tell you how to check your air control valve to see if its bad. I was amazed at how one little piece could change emissions so much. (Just for info when my acv was bad, my car also had a little misfiring on deceleration.)