My 2004 Cayenne S with 150K miles has been great. But, the other day, as I was backing out of my driveway, nothing happened when I put my foot on the accelerator. The car continued to roll in reverse until I stopped it. I started it up without any problem, but when I put my foot on the accelerator, I was able to drive about 2 feet and then the engine quit again. I started it up a 3rd time without any problem and was able to drive back into the driveway before the engine quit yet again. The Check Engine light never came on, and no warnings appeared when I checked the Vehicle Info. I took the car out yesterday for a very short distance and everything seemed ok. Does anybody have any ideas about what caused this problem? thanks!