Why does leaving the gas cap off cure the problem?
March, 25, 2012 AT 3:55 AM
You have a problem with the vent on the fuel tank. You can try getting a new fuel cap and tight will hopefully fix it. If not, you will have to look into clearing the gas tank vent as it has become cloged somehow. This may also be happening in the EGR pipe system near the exhaust and causing the same situation. You may also have a larger blokage in the exhaust itself at the catalytic converter, but leave that aside for now.
Check EGR lines and get a new fuel cap. Do each fix one at a time to see which one cures the problem.