My check engine light has been on going on two years now. on 2007 Chevrolet Cobalt

It codes as a cylinder 3 mis-fire. I had all of the spark plugs changed and the check engine light is still on. It took 3 inspections before it finally passed. When the gas tank is full It feels like it runs better and I don't feel it misfiring. Has anyone had any experience with this?

by in New Caney, TX on March 13, 2014
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2 answers
ANSWER by , March 13, 2014
Possible weak fuel pump, have seen that before.
ANSWER by , March 13, 2014
try a higher octane gas next time you fill up.