2003 Honda Accord Car does not start

Car will turn over but will not start. This has happen
several times, then it starts the next time. Car was taken to dealer and they could
not find any problem, except the battery was not good and the battery was replaced.
The dealer even suggusted using spare key, this had
no change
The last time they replaced the "idle valve" per the
computer. The car starts now but this makes no sense
to me.
Do you have any thoughts on this problem?
Thanks,
JR