2009 silverado 5.3 rough idle misfire 7

This sounds like a fuel quality problem, before spending any money on repairs fail the tank with Chevron mid grade fuel and drive it around and see if it improves. As the system had been open for so long there could be corrosion in the lines, so just hope it is minor and the Techron in the fuel will work. When you’re ready to fill up again go back to regular gas. No reason to spend money on higher octane when the engine doesn’t need it.

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The EVAP system code could be a vacuum leak. Check your vacuum hoses for damage or being disconnected. If your truck sat outside for the year you didn't use it mice or a squirrel could have moved in and chewed up a vacuum hose. Also, the EVAP system is involved with the gas tank and fuel pump assembly. So you could have a loose vacuum hose there. With the one cylinder misfiring it could be a sticky fuel injector from sitting. They can get gummed up. Hopefully the Chevron Cleaner will get it working again. In the meantime make sure cylinder number seven has spark. If it does, compression test that cylinder. If compression is good, around 150 PSI or higher, then it's going to be the fuel injector. Oh, check the spark plug wire, if applicable, going to cylinder number seven as well. Rodents like to chew on wires too! Hope that helps! Jim

If you've been driving it for that long, I think it's gotten enough fuel through it to clean up anything in the lines. When vehicles just sit unrun for so long, things happen to sensitive parts, like electronics. Now you do need a mechanic. Have a good mechanic diagnose the problems, show you the codes and explain what's related. That shouldn't cost more than a couple hundred bucks, but then you'll have all the directions you need to do the work yourself..... Sorry to hear about your predicament, but this will be the least costly way to go and the quickest way to get the truck back to running right.