Cleaned the modulator. I'll remove the egr to check

 

Do you have a vacuum pump? You can tests these components by applying vacuum.

Apply Vacuum to the EGR valve, if your engine stumbles than the EGR valve is good.

To check the modulator to see if it gives the vacuum to the EGR valve. Pull the vacuum line off the EGR valve that goes to the Modulator. Rev engine, if the needle on the vacuum gauge moves the modualtor is good. If the needle doesnt move, most likey you have a bad modulator.

I would replace the modulator with a new one, I dont see cleaning it would help.

You know I just realized that you had the V8. It also can be your O2 sensors, if you have a lean condition NOx will elevate.

The cars that I see fail are the 4 cylinders and the V6s, the common problem is the EGR modulator

 

I'm going to give this a try. But being that no cels came up. I'm leaning more towards it being egr issues then o2. Hopefully its the egr system.

 

I you don't have a vacuum pump, just hook up a vacuum hose and suck on it.

Good luck with this issue, you've seen my thread and I am leaning now fully towards the o2 sensors being my problem.

 

Discovered this when I went to clean my egr lines. Don't know how i missed it before. Damaged VSV. Maybe this is part of my prob?

 

That could be the culprit. The VSV controls the EGR modulator at certain temprature and driving conditions. Without that, the EGR system wont function correctly

 

Not to mention having a vacuum leak makes your car run lean.