92 Camry V6 3.0

Where are you located?

I have never heard of HOx. Assuming you mean oxides of nitrogen (NOx), your vehicle did not fail because of low NOx because lower is better.

The high HC and CO could be caused by an ignition system misfire, which could be related to the spark plugs and spark plug wires you recently replaced. Did you use OEM spark plugs and wires? If not, I would start by using OEM plugs and wires.

Hydrocarbons (HC) are unburnt fuel, and so high HC means high amounts of unburnt fuel, either because the fuel is not burning completely or the mixture is too righ - that is, the fuel ratio is too high for the amount of air

High Carbon Monoxide (CO) comes from a fuel mixture that is too rich.

The combination of high HC and CO could be caused by a misfire - one or more spark plugs are are not firing; incorrect ignition timing, or a righ fuel mixture.

How does the engine run at idle? Does it run smoothly? Does it idle normally or fast after it is warmed up?

Why did you replace the distributor? How long ago was it replaced?

What is the condition of the air filter? If you shine a light through it, can you see light?

What is the condition of the black plastic tube between the air filter and the throttle body? Is it free of cracks or holes or leaks where it connects to the air filter housing or throttle body housing?

A competent technician or your Toyota dealer can also check O2 sensor operation since it controls the air/fuel mixture.

Dear Ray,

The eng> > Dear Ray,

Hmmm, I've never heard of a distributor being replaced as part of a tune up, although distributor caps are replaced.

I think the dealer will have to check the O2 sensor function and if that checks out, check ignition system function.

If, as the OP noted, the entire distributor and not just the cap, was replaced then I wonder if the timing is correct. FWIW YMMV