What does your teacher have to say about this problem?
Overall, I'm guessing you've jumped into playing this too fast, without having done the preliminary slow and careful pre-work.
I see you've worked on no 41 which is also for the LH - - did you have tension problems with that one?
I'm curious, is it a LH only issue? How about op 740 no 50 - that's quite a demanding piece for RH - did you have a tension problem? If not, study what the RH is doing right, and the LH is doing wrong.