why would the engine not start back after turning off? on 1999 Mercury Sable

This has happened 3 times in the last year. After a few sitting fore some time (hour or so) it starts back.

by in Farmington, AR on August 21, 2014
1 answer
ANSWER by , August 27, 2014
Possibly a crankshaft position sensor, about $20 at AutoZone