It would appear that your chain is two years old based on the year of your bike and the questions that you have posted would lean towards minimum expeirance in mechcanical department, no harm intended.
I would suggest new chain and sprockets and go from there. Once worn, steel against aluminum, they won't mesh properly and the chain will jump around like you have said. An old chain can be stiff and have tight spots from corrosion too.
If your not a racer and losing a small amount of power isn't going to kill you then get an O-Ring chain and steel sprockets, that should solve your problems and they will last a very very long time with minimum maintenance required.