1982 Chevrolet El Camino hesitation

First check for leaking vacuum hoses, but most commonly a stumble on acceleration is caused by weak accelerator pump output. If you have a Quadrajet, the linkage going to the accelerator pump can be bent slightly so it takes a longer stroke. That will give you more fuel to prevent that hesitation.

If your engine doesn't call for premium fuel, you're spending extra money needlessly. Higher octane gas does not produce more power. It is simply harder to ignite. That allows engine builders to design an engine to produce more power, but the drawback is increased spark knock. The higher octane reduces that spark knock.