97 Sable sometimes just doesn't want to start, lots of fuel at the Schrader
valve and pump is working. Here's the weird thing , this car has had 3
crankshaft position sensors in it  the last being only about 2 months ago.
Immediately after you replace the c.p.s. the car starts right up. Today it
wouldn't start and we gave it a shot of quick start down the intake hose and
it fired right up and has started all day long ever since. Any Ideas what
the root of this could be? Sensors are always factory Ford.

Tanks in advance, Dave.