It turns over fine, but won't start?

What is your question?

I drove about 15 miles to my sister's house, parked and when I was leaving, the engine turned over just fine, but it wouldn't start. It seemed like it wasn't getting gas or like when the older cars would get moisture in the distributor cap, there wouldn't be a spark. The next day when I went back to my sister's home to meet the towing service, it started right up. I took it directly to a German garage and they couldn't find a thing wrong. So the next time I drove it, I stopped to put flowers on my wife's parents grave site & when I tried to leave, it did the same thing as the first time. Turned over fine, but wouldn't start. We waited for about 5 minutes and it started again, but it struggled a little getting going. We drove 50 miles with no trouble, but this morning it won't start again. Can anybody help? The car shop ran extensive tests on it saying they couldn't find a thing wrong.