maz_pr03

Hello all, I am new here and am here specifically to ask for help with this. I have a 2003 mustang gt. the motor gave out on me so instead of doing work on it I just bought a motor with lower miles to swap in. Before swapping it in I changed the timing components, timing cover gasket, valve cover gaskets, intake manifold, and i believe that is it. one big thing is that after it was said and done, we realized that the motor was seized (rookie mistake, my first engine swap so we left it outside not too well covered) but a shop freed it for us and it runs. the only problems are: runs extremely rich, so rich that gas leaks out on the passenger side valve cover, through the exhaust, and also into the oil. I changed the oil and have not started it since that discovery. the oil was not milky, but was thinner than usual. another thing is i tried scanning it with my obd2 scanner, but it could not recognize what kind of car it was. is this normal and just need to take it to get a proper tune, or do i have deeper problems? any and all help will be greatly appreciated. the new motor came from a 2002 mustang gt with an auto transmission while my car is a manual. I kept the manual.