NEED HELP ASAP 1998 CBR F3?

Need helpwith my bike. I bought a 1998 cbr f3 that has been sitiing in a shed since last summer. The bike originally didnt start, I bought a new battery and it cranked but didnt turn over. I dropped the fuel tank, flushed the fuel and replace the fuel filter. Air filter is FILTHY and I havent had the chance to change it yet. I think it still needs a carb job as well. I everntually got it started and it ran fine for a day and then the next day after riding for an hour, it just cut off. I tried starting it but it was backfiring badly and it did start several times but as soon as I put any time of throttle it shut off. Eventually it started again but the same problem happened again. If I rock the front end/pull body weight on the front, it seems to help but still runs rough. What could be the issue? I also noticed what seems like a vacuum hose thats UNattached on the left hand side towards the front fork, any idea what its for?