There is a very good chance that poor chainline (chainrings too close to the frame) is also the primary cause of your shifting woes. It could be that the bike was built with the wrong BB cartridge. Is it practical to take the bike back to the shop that sold it? If not, a well-equipped mechanic can install spacers under the RH BB cup to improve chainline. Worst case, you will need a new BB to give good chainline and centered pedal "tread." But I'd try the spacers first.