I have a 2000 XK8 and twice in the past few weeks I've encountered a condition where the car starts and runs fine from home. We stopped at the store for a half hour and when I went to start the car, it would start and immediately shut off. No CEL or error messages presented. I discovered if I depress the gas pedal a bit, it started and kept running at a 2000+ RPM rev although rough at first, but after maybe 5-10 seconds it smoothed out and then idled and ran fine after that. The air intake nozzle from the air cleaner box to the intake on the throttle body was replaced last year, as well as the MAF sensor and air filter. I suppose a vacuum leak isn't out of the question but think that would be a constant problem that didn't resolve itself. The only other thing I can think of is because this car is a garage queen between November and April, the gas in the tank is almost a year old. This feels like a fuel problem, not electrical.