I have a 572ci blown motor, 900hp on pump gas, in a 26' daytona that has about 50 hours on it, and has run flawlessly. The boat hasn't been used for four years. It has an MSD ignition. I had drained all the fuel at the time I parked it. I took it out this weekend after changing the oil and plugs and installing new batteries. After driving about ten miles the motor sneezed thru the carbs, and again after about five more miles. The only thing I did different this time was I blended in 15 gallons of 114 octain race gas, about 9 months old that I wanted to use up, with 50 gallons of 91 pump gas. Could this have caused a lean condition and caused it to sneeze?