06 cobalt lt no upgrades other then a k&n air filter if you can even count that 72k mile work car that goes up and down a 27 mile hell trip to work and last two tanks of fuel I've noticed a loss of power and fuel economy dropped all plugs look fine filter cleaned and new fuel filter with no difference gonna clean MAF sensor anyone have any suggestions? also I started running 89 octane fuel from a sheetz when I noticed the loss which should be a no brainer but should'nt that be better?