As with the rest of the gang, make sure it is a Maintenance Free battery (it doesn't have anywhere to add water). All the parts stores (including walmart) show that a wet cell battery will fit our bikes, but in reality, they may only work for a couple of weeks at the most. You'll need a Maintenance Free (MF), also called an AGM battery.
Assuming that it's not the battery, it could very well be your charging system.
As to the misfiring, you'll probably need to clean the carbs. I'd try doing a search in the box above for gumout, and review the procedure to "backwash" the crud out. Here's the link: http://vn750.com/forum/showthread.php?t=8345
If that doesn't work, you may need to pull the carbs. Personally, I'd recommend letting the shop do it, unless you are REAL HANDY with mechanical stuff.
BUT, before trying the gumout and carb cleaning, try the SeaFoam as per HyperBuzzin. There's nothing like it, so don't use just any gas treatment. Add about an ounce per gallon. You can get it at most auto parts stores, it looks like this:
Run through a tank with it, and see if it helps.