Here is a test. Next time the car turns but doesn't start, check to see if your power windows & the HVAC blower motor work. If they don't, then your problem is either the ignition relay which is in the fuse box under the dash(about $4.50)or your ignition switch(about $25.00). Most likly the relay would be at fault.
I had the same problem with one of my Contours recently. Once I found the problem(after following the wiring diagrams in the shop manual)I relized that some Contour owners probably took their cars to the dealer for a simple fix and ended up paying for a fuel pump and/or PCM. Atleast that seemed to be what everyone was telling me here on the CEG boards that they had done to their cars to fix the same problem. I knew the fuel pump and pcm wasn't at fault with the symptoms that I had.
I wouldn't change any parts until you actually have the no start problem again(this way you know it is actually fixed). It doesn't hurt to carry a relay in the glove box though. In anycase I hope it works for you.
Al
