Another "intermittent" can be the safety switches that prevent starting in gear.
Don't know what trans. you have, but there is a system for both automatics & manuals.
For example, my S-10 P/U JUST developed an intermittent start problem where it might not crank at all. After checking things out Sunday evening it was traced to the switch that allows starting when the clutch pedal is depressed.
Emergency fix that night was to bypass the switch so it works at any time - like an older vehicle without safety interlocks.