The crank position sensor affects running as well as starting. I would
think it would be dying and running poorly, not just cranking without
starting.  Here's some good info from Dr. Bob on the crank position
sensor:

"The crank position sensor is the hall effect sensor pointing to the
front of the crankshaft.  The hub behind the front pulley has grooves
machined in it, with one groove missing.  the sensor reads each of the
pulses from the grooves to know exactly how far the crankshaft has
turned,   and reads the missing groove to re-identify a known position
to reference from.

This allows the ignition and fuel injection systems to make sparks and
fuel at the right time.

There is a 'limp home' mode, as you have discovered, that allows the
engine minimum operating ability so you aren't stranded.

A failed sensor generates an error code, so the diagnosis is fairly
straightforward.  If you weren't at a Ford dealer,  the $200 is the
result of not having the right code reader.  The sensor takes mere
minutes to change."

Here's a description of the problems it causes:

"The crank sensor went out last fall on our '92 XL, too. The car would
suddenly die and wouldn't start again. After about 10 minutes, it would
start up fine and run like there was nothing wrong (until it would die
again, usually days later). Finally, it would run only poorly (the
"limp home" mode, I guess)."