Next time it won't start right up, give the OVP a few taps..
..and as I said before , see if your car still has the old style OVP in there ..that is direct 12 V power feed for the Engine Management and a fault there will result in your condition.
The old one is 000-540-52-45
The upgrade replacement is 000- 540-67-45
It is behind the panel, behind the battery.
Also, do you ever see a flicked of the ABS lamp????? If yes, that makes OVP evem more suspect , as that same OVP is also ABS module feed.
http://www.peachparts.com/shopforum/showthread.php?threadid=54371&highlight=faulty+ovp+part