I got gas this morning at the usual place a Chevron station locally where I live and headed down to FCA Concourse at the Quail Lodge. On the way down there after 30 - 40 miles I noticed the car is hesitating at the about 7k rpm under acceleration otherwise ran o.k. Concerned about the problem, on the way back I stopped at a local shop and explained the problem. He took the car for a ride and noticed the same thing. He hooked up the sdii and his laptop and we went for a ride. He immediately noticed both knock sensors were showing faults. He also checked everything else (variators, throttle position, air induction, etc...) all normal. I suspect a bad case of gas at a reputable station. Under his suggestion, I filled up the tank, it was 3/4 empty and added the redline additive and suggested to put some mile before it goes away. I drove home about a 25-mile drive the car still feels the same way. I am going to the track this weekend and like to get this fixed as soon as possible if it is not the gas, any suggestions. Thanks in advance.