Motorcycle Repair: Kawasaki vulcan 500 1999, kawasaki vulcan 500, couple time

Question
I had a vulcan 500 1999 with 3999 miles on it!  I bought it couple yrs ago from a family friend which he had it sit it in the garage which run very smooth!  
This winter i put in the stabilizer and i use to start the bike every week and take a it for a short ride!  But i have not start the bike since xmas!  So i start the bike this week but there is a problem.  After I start the bike and take it for a ride I feel the bike rpm won't go over maybe 3500 rpm. I hit first gear and i can feel the bike is not really moving as it use to which i feel that the engine had hold back on me!  then i try to switch to second gear see if that go any faster then (25mph) which it won't and almost die on me!  So, I pull aside and let it warm up a bit more "about 5min" so i go again which same thing happen!  It just won't let me go to higher rpm. i try it couple time and one time which go like normal maybe for 2 second, then you can feel the bike die down again its like that is not enough gas or electric to go to the engine.  can you please tell me what is the problem and if i have to take it to the shop and fix it, how much will cost me!  Cause I bougth my bike very cheap i don't want to spend too much to repair it

Answer
This is a long shot, but do you store your bike outside? Squirrels and mice have been known to make nests or store food in airboxes and mufflers of motorcycles... what you describe sounds like the motor isn't getting enough air, so check the air filter to see if it is plugged. If that is okay, try draining the carbs and gas tank and fill it with fresh fuel.