The melody line in the pre-chorus is pretty straight forward, the reason I isolated this section is due to measures 17 and 18. Here, we see a run that rhythmically, seems rather... sloppy, in a sense. It's intention is to "float" over the beat, simply to be played fast and to occupy a certain amount of time without locking into straight 16ths or any form of tuplet. Practice this lick slowly and evenly so that the technique falls in line, and then... just go for it! Working hard at pin-pointing where the lick falls over the backing track in any sense is doing the lick a disservice. Be free!