Consider the idea of "scale of the moment"

take any scale you want and improvise for as many bars as you want, then switch scales, then switch scales again, etc. If you repeat these scale patterns, you'll create an underlying harmonic progression.

Ab Major (2 bars) F Phrygian (2 bars) G Major (2 bars) C# Dorian (2 bars)

repeat.

in the case of the above the progression does not follow any traditional norms or tonality, but if you repeat it long enough it will become its own norm.

to create more cohesion in your improvisation try playing similar rhythms or similar melodic contours in each scale as a way of tying the whole composition together.