Autozone ran a diagnostic and two of the three problems came as a knock sensor issues. The third was a problem that the emissions said the guy was insignifigant. He recommended adding a pint of Sea Foam in my next tank of gas, which I did, but not solve the problem. I do not know much about cars. Does this mean that the knock sensor needs to be replaced, or that the sensor is the identification of a problem in the engine needs it? Also I just noticed the other day that there is a sticker from the gas cap, which recommends premium fuel. I use regularly. Could this be a part of the problem? Is premium fuel really necessary for this “not-so-high” performance engine? Thanks in advance for any advice.