Ah.... the fun of CO Emissions. I cringe everytime I go in to test the cars as I will have always performed some mods that make me ride on one cheek to the testing station. My 95' S351R Saleen with the 408 Stroker and Vortech is always fun, but just passes every two years.
Not sure what to do on the Viper but from your readings you need to lean out the car to pass. If you have changed out all four O2 sensors and put new plugs in already, the easiest trick I can think of is to add three or four bottles of Methanol to your 1/4 full 91 Octane gas tank. The Methanol in the gas will help it pass emissions much, much easier. It worked on my blown S351R the past six years. Pep Boys sells it as "guaranteed to pass emissions".
If you are failing on the idle test, then you might way to come down south during the week and run the car past the mobile Emissions Testing stations. They are usually at an on ramp at Quebec and C-470. I believe you just need to drive by it two or three times in a day or over a couple of days (please check first). I am not sure how they test all that, but it would make sense if it eliminates the idle test because the car is not idling. It will register as pass or fail at that point. If it passes, it is already in the system and nothing more to do but pay an extra $25 at registration. There is a Pep Boys right there and you can load up on the Methanol right there. With hot cats, it might just work. Just work is all you need.
If that does not work, the I suggest putting in a stock tune for the computer and see if that helps to lean it out as it is clearly running rich to protect against knock and to keep it running cooler. It might get you through the test, then you can tune it back to run right. Just don't push it on stock tune.
Finally if that does not work, find a friend in the mountains in a non-testing area and work it out with him so you can stage the car being stored there. Emissions testing in Colorado is per where the car is stored and resides, NOT where you physically live. If you can make that work, then no more emissions testing for you. Pueblo is the same thing. It is good to have friends, though I have never gone that route with my cars, I know people who have. Might want to clean your injectors as well beforehand.
Hope that helps! BTW How old is the gas in your car?
