Porschedoc, I have a 2000 Boxster s with tiptronic gearbox. Drove up to roundabout and car stalled. Engine turned over but no firing or start. About 20 minutes later car started first time. Drove for another 15 mins and car stalled at lights and would not start. Car started fine next morning. Have checked vacuum system and seems fine. Cleaned up throttle valve. What else could it be?.

 

I would suspect a bad fuel pump or fuel pump relay.

 

PorscheDoc, Sounds logical. Have changed both and am keeping my fingers crossed. Thanx for the advice.