Alternator/generator/regulator problems of the 2004 BMW X3

I purchased a 'certified" BMW 330i in December of 2006 and have had the fuel pump replaced, instrument carrier replaced, both passenger window regulators replaced, sunroof repaired, headliner repaired (it just fell down one day). The car won't start right up, and when it does it runs real hard and the rpm goes up suddenly, the car takes a minute before it will even move & then it does so fast! I have had it in several times with this complaint and they can't diagnose what's wrong with it. I was told that the computer isn't showing anything, so it will have to get worse before they can diagnose it. Wow! I've only had the car for 8 mos. And I've been to the dealership more times than I can remember. I'd like to know how they determine a car to be certified? it sure doesn't seem as though it was checked too thoroughly to me. And OH did I mention I had to take it to goodyear today for defective tires, that BMW wouldn't cover. Thanks goodyear at least you stand behind your products! this is my 2nd BMW and my last! please feel free to share this to BMW of north America!!!.