I initially failed my emissions test, luckily I was in a shop where they let me use my laptop under the retest.
To pass, I leaned the truck out at idle from 12.4-13:1 to 14.7:1. The leaner I got the more cranky the engine became, but 14.7:1 is still reasonable.

If they test it at fast idle, stalling won't be as big of a deal. You could lean it out youself via a vacuum leak as you've mentioned. If it leaks too much, it will stall, so connect that unplugged vacuum hose to some sort of small filled pipe that you can drill through. IE - take a small pipe, fill it with epoxy, and then drill that hole out slowly until you get to the point where the truck isn't runnin very well, then reexpoxy and go back one drill bit size... Consider it idle air jetting.. :-)

I honestly don't know if the 02 sensor is active at idle. Most vehicle disregard 02 sensor readings at lower RPMs, so I suspect the 22RE is like that. To test, take a reading from your 02 sensor (which is under the drivers seat, typically) and see if it fluctuates back and forth across .5v fairly quickly.. If not, tell us what it reads. Note - do this after the truck is warm, not on initial start up.


Getting a working cat would be the best option, but I know they can be expensive. No experience with the additives that are sold for the purpose of passing tests like this, so you'll have to do your own homework.

Going from 300 to 200 is a 50% reduction in hydrocarbons.. That's going to be tough.