too many guys get caught up in the idea that the guitar is somehow designed to play random licks and as fast as possible.
What you should be aiming for is to actually create a sort of melody during a solo. Well not so much a melody, but a main theme.
And to top it all off, you need a start, a middle (the most intense part) and an ending.
I would also recommend to STOP practicing scales the normal way (root, 2, 3, 4, 5, etc) and instead practice "contouring".
So for instance, take a minor pentatonic and start your metronome and instead of playing 1,m3, 4, 5, b7, play 1-4, m3-5, 4-b7, 5-1 (also called playing "in thirds")
Make up your own patterns and practice them. raise the speed on the metronome each time, and don't play the same pattern two days in a row. This will help to improve the spontaneity in your solos, I guarantee it.
I have the same problems sometimes though (every guitarist does). you can't get past the fact that you will inevitably use certain patterns more than others and this will be "your sound". If I hear Santana playing on the radio, I know it's him immediately. Why? because he uses very distinct patterns in his solos, and he uses these patterns REPEATEDLY.
From analyzing my own solos, I've noticed that I stick with the pentatonic alot, and unlike lots of guitarists who use mostly 1,3,5's, I use a lot of major 7 notes over chords. A little too much actually. So if you're aware of what you play then the next time you solo you can stray away from the usual and try something different.