hey Hardo, welcome to pS, whu dnt you post your recordings here like i do. your 4th finger is weak, so you need to play the speed that you can control the notes evenly and fortate/slow is the way to go. Otherwise, get inoto some hannon or Czerny execises like Perferct Pitch did for finger strengthening... This is just a start...
Looking forward to your first chopin study....