Respected Sir, this car came with the prosmatic if i am not wrong. that if in perfect working condition, locals at 5500rpm in N and 6200 in D, D3, D2. there is an electrical fault in the gearbox.
Since you have switched the gearbox, you should change the ECU as well so that it reads the manual transmission. or better yet, since this is a recent job, return it and get another auto gearbox. that would make it easier