1992 Kawasaki EX500 having some issues.

Bought the bike a couple of days ago, they guy we bought it from said he rode it less than a handfull of time and then it started making a noise and he just stopped riding it. The noise was the chain. Easy fix. But then it started missing gas everywhere. Ordered a new carb kit. It's 2 cylinders. Stopped missing gas. Now when we start it and rev it up, it nearly wants to shut off and make this cough like sound or like it's not getting enough fuel or something. We checked the spark plugs, they should be replaced but everything is currently closed now. The floats seem fine and leveled and the cylinders seem to be in sync now. It's an older bike with 29k miles on it.

Don't know what else could be the problem... Anyway helpful hints or pointers?