Q: Car running rough and shaking

Hello. I think the "fuel tank being open" you are referring to is a code for the evaporative emissions (EVAP) system. This system is used to capture fuel vapors and prevent them from entering into the atmosphere. If the powertrain control module (PCM) detects a problem with this system, it will illuminate the Check Engine Light. There are many different codes that correspond to the EVAP system. The cause of these codes can be anything from a loose gas cap to a pinhole in an EVAP line. The EVAP system can also be responsible for an engine misfire if the system purges at the incorrect time. However, your EVAP code and misfire code may or may not be related. This is because there are countless of other problems that could cause an engine misfire. I suggest you have a trained professional, such as one from YourMechanic, diagnose why your vehicle is shaking and replace any failing parts.