I have a 2003 G35 base with 145K miles. On a couple occasions over the past 6 months the engine simply stops without any notice or hesitation. After pulling over and sitting for a few minutes it starts, however it is not the crisp smooth start as usual. Once started it drives fine. About 6 weeks ago I was leaving the house for work and it wouldn't start. When turning over the engine I could tell it was like it had stopped as just described...not crisp & smooth. After some internet searching of these symptoms I replaced both cam sensors and the crankshaft sensor. In addition, I thoroughly cleaned the throttle body & MAF sensor, as well as replaced the plugs. I also reset TB and relearn idle. Now I am able to start it but the turnover is still not crisp. Once started it idles well and I'm able to rev the engine for about 1 minute. After 1 minute the rpms drop significantly and the engine sputters terribly. The SLIP, SES, and VDC lights all come one. RPMs will bounce up & down and engine will shake & sputter (almost backfire) for another minute or so until it finally stalls. I've attempted to drive it to the auto store to see what codes are being thrown however it always stalls before I'm out of my cul-de-sac. I don't believe it is a coil, injector, or fuel problem because it starts and idles. Logic tells me a vacuum issue. Am I barking up the right tree, or should I focus my attention elsewhere?