I don't usually say this. O.M.G.
I recently reviewed Gallo Blanco Cafe in Phoenix, which fell into the "cleaned up but still cheap" category of Mexican food. Tolteca is definitely in the "local grimy Tacqueria" category. And it's one of the best I've ever been to (including in LA and SF).
The carnitas burro blew me away. Fresh, homemade flour tortilla makes a huge difference. Carnitas were incredibly moist and tasty. Fresh guacamole, great salsa. Everything about this dramatically more delicious than your average Tacqueria burro, while still being simple and not just trying to win you over with loads of sour cream and cheese.
Save room for dessert, too - they have a great pastelerĂa too