about the gas

Is it diesel you put in the engine or lower octane gas? If its diesel the tank needs to be drained and fuel filter replace. If it is lower octane gas, don't drive at full acceleration or load use 1/4 tank fill with premium fuel and fill again when it drops to 3/4 full and you will increase the octane of gas in the tank. Knock sensor will automatically retard timing to prevent engine damage. I wonder if you just got bad /water in gas. Get a professional to drive the car and give their impression.