I have / had the same challenge.
Fingers and tongue need a lot of practice.
I made two experiences:
It is very important to practice very slowly. When you believe that you can manage that tempo then practice one week longer before you try faster.
Sometimes we block us by ourselves when we think about coordination of finger and tongue.
It depence whether your exercises is process or result driven.
When it is process driven than you can try to play as fast as you can without judging the errors. Your body is able to fix them automatically by time.