When you get confused when rolling through a song, go back to just doing rolls.
Unlike many books and teachers, I recommend playing rolls FAST.
Don't play them uneven. Make sure you get each note as far apart from the others as every other note.
Sometimes this is easier to do up-to-speed.
Try drumming your fingers unevenly. It's almost impossible.
And actually, if you think about it, you ought to be able to roll as fast as you drum your fingers.
Just takes practice.
The other reason I suggest playing fast is that it's easier to hear the melody.
And it's harder to think of each note separately.
You're much better off thinking of the 8-note roll as a complete unit.
Makes keeping your timing easier and lets you focus on other things.
Here are three basic practice tabs. They use the same TMTIMTIM but each hits different strings.
Thinking of them as 3rd string or 2nd or 4th string rolls helps identify the three important melody strokes.
Here are the same rolls on the same strings but using a C chord
Here are rolls to practice that "switch" strings.
The two Index strokes may be on different strings from each other or from the first Thumb stroke.
The Middle finger and last two Thumb strokes always hit the same strings.