2010 Suzuki SX4 persistant misfiring issue

I have a 2010 Suzuki SX4 that has had a persistant electrical/cylinder misfiring issue all year. It started as a misfire code, so i changed all the spark plugs. Runs fine for a few weeks then begins misfiring again. I changed the ignition coils twice this year and the spark plugs three times. Every mechanic I take it to either says its fine or just wants to change out the plugs/coils again without looking for the issue that is causing them to burn out. But i know its not the parts, its something affecting the parts, some under lying cause. The plugs only have a few months of use on them and they are already burnt on the white part. I live in a small town so i exhausted the mechanics i can take it to, and i only have a small amount of experience with working on cars. Would a bad alternator cause this? Is there too much power being sent to the cylinders? Any advice on a direction to go in solving this problem would be greatly appreciated. What would cause my plugs/coils to keep burning out, causing misfiring and the engine running rough?