Problem with starting intermittent.

I have a 04 vivaro. Some mornings it won't start, but if you let it roll about ten feet and bump start it it will go.
It might start all day but then it might not start out if the blue

I have changed crankshaft sensor and cam shaft sensor. Also but a new priming bulb before filter and non return valve in the line.
But still does this

Has anyone got any suggestions??

Starring to lose faith in it now.