I live in Dallas also. I had a 1983 Landcruiser that could not pass emissions test, even after spending over $1,200 in repairs. I finally spoke with someone either at the DPS Field Station in Plano, or with AirTechTexas. They said they have a location where vehicles that have repetitively failed inspection can be brought and this location has a 95% success rate.
It is a state facility, not privately owned. I spoke with the guy in charge, and he said they were finishing up a Ferarri that no one else could get to pass emmissions. I will try to find the number for the facility. It’s been a couple of years.