2002 Pontiac Montana won't start when luke warm.?

This is probably not going to be for amateurs. First a little about me. I have over 50 years experience repairing cars of all kinds. Unfortunately I stopped working on cars for living about the time computer started controlling everything.

I have a 2002 Pontiac Montana with a V-6 and about 130,000 miles. Most of the time it runs very well. Three times in the last week it has failed to start. All three times was under about the same condition. The van had been running for about 5 min. it was then shut off and it sat for less than an hour. When trying to started it with turnover very well. Every time I turned it on I could hear the fuel pump running and it shut off when reached pressure. But absolutely did not even try to start. I went inside and had a cup of coffee and it sat for another 30 min. when I went back out it started up as if there was absolutely nothing wrong with it. Weather conditions all three times were a little different. The first time it was snowing and cold but the car sat in a 55° heated garage. The second time it was about 25° and the car sat outside in the parking lot. Today the temperature is about 50° and sunny. All three times the engine did not completely warm up before I shut it off and he did not sit long enough to completely cool off. I am assuming from the way it acts it has no spark. I have tried turning the key on waiting for the fuel pump to stop turning it off and then repeating that process five or six timings thinking that maybe if it's fuel filter was plugged I did force enough fuel through it to at least make and tried to start, it does not. Once I give it the extra half an hour to cool off it starts up and runs like a clock no problems running at highway speeds or anywhere in between it runs smooth it does not hesitate. Does his is vehicle have a low oil level safety switch that would shut it off at the oil level was low? The only thing I can find is that it is almost a quart low on oil. My thought was if the oil and engine were cold it would remove enough oil from the pan and it would take a while to return and that safety switch would think it didn't have enough oil in it. Can anybody out there help?