Engine dies when the car comes to a stop

Engine Performance problem
4 cyl Front Wheel Drive Manual 193648 miles
Hi! Recently, my car developed a problem where the engine dies when the car comes to a stop.

When I start the engine for the first time after it sits all night, it doesn't die at stops until I've driven maybe 3/4 of a mile or so down the road (I assume because the engine has had a chance to warm up). After that, even if I let it sit for about an hour or two and then restart the engine, it continues to die at stops. If I keep my foot on the accelerator to slightly raise the RPM, I can keep it from dying.

I always put premium rather than regular in the car. Always have. If, for example, the gas station were to accidentally put a lower octane in my car, would this kind of a problem arise?

If not, what might be the cause and how could I fix it?

Thanks in advance!