Break difficult passages into smaller sections. Try it using my four phase Guitar Workout strategy to practice these sections.
I. Play the part very slowly at first (fundamentals).
II. Play along with music to get a feel for how it works in the song (musical exercises).
III. Increase the speed beyond where you can comfortably play it (out of the plateau).
IV. Play the passages in different positions using the entire fretboard. Connect them to other licks you have learned and integrate them into your playing.
Now that you have the difficult passages mastered, play along to the entire song, or backing tracks — this way, you can get a feel for how it works within the song.