It's not easy to say what is good fuel. It may depend on the particular gas station, and whether they keep it clean, as much as on the brand.
I would suggest you buy a bottle of fuel injector cleaner (costs about $2), and dump it in the gas tank when you fill up. That should clean up the injectors.
What is the idle rpm when the engine is cold? (And tell us how cold it is in Fresno, these days). One possibility is a faulty coolant temperature sensor, so the car's computer doesn't know that the engine is cold, and is failing to raise the rpm and the richness of the fuel/air mixture.
If you are feeling a little adventurous, you can read what your car's computer is telling you (if anything) about this problem. Here's how:
Look under the hood, next to the fuse box, and find a little black box, about one inch square, with "Diagnosis" written on it. Open the lid of that box, and read the sticker under the lid to locate the T and E1 terminals. Get a paper clip, open it out into a U shape, then stick one end of the paper clip in the T terminal, and the other end in the E1 terminal. Turn the ignition key to "on" (do not start the car). Watch the Check Engine Light flash. Count the flashes. A long flash means ten, and a short flash means one. So 2 long flashes followed by 3 short flashes means 23, for example. If you get code 22, I guessed right, and you need a new coolant temp sensor.
Toyota Tercels are very reliable.