Try taiko if you have trouble keeping rhythm during streams. If you can't keep a stable rhythm then how can you hit those super hard streams.
If you can play the map on taiko without trouble, then you can focus on actually moving along the notes. Where the notes are on the playing field for the most part is irrelevent. If you can find the beat you know how to hit the notes no matter where they are. Taiko will remove the locations of the notes and allow you to find the beat. The beat of the song will then instruct you how to hit the notes.
After that its just practice until you can play to the pace of the difficulty.
If you can play the map on taiko without trouble, then you can focus on actually moving along the notes. Where the notes are on the playing field for the most part is irrelevent. If you can find the beat you know how to hit the notes no matter where they are. Taiko will remove the locations of the notes and allow you to find the beat. The beat of the song will then instruct you how to hit the notes.
After that its just practice until you can play to the pace of the difficulty.