Have been having some engine problems for the past couple of years on a mitsubishii eclipse with current miles at about 100,000. Car won't pass Maryland emissions. Checks run on the engines computer say that a code is missing that should be there. Only explanation is when having problems, my mechanic purchased a computer from dealer and wrong computer sent. Then when received another computer, code missing. Will a new engine with computer resolve this issue?

Optional Information:
Mitsubishi Eclipse

Already Tried:
dealer, various car repair places, internet