it will start and I will drive it for about an hour then it turn off it will take an hour to start again what it could be? Thank you

I saw your question earlier this afternoon and was thinking about it for awhile. Called a few other real BMW techs. One said sometimes the O2 sensor gets a metal flake on it and taking it out and cleaning it out with compressed air fixes them right up. He had a story how he figured this out. Its an od ball thing and is very rare to happen (I see another guy suggest the O2 sensor) But I have been driving REAL bmws like yours for years and have never ever ever had a REAL bmw let me down. When the newer junk BMWs came out I bought a 1988 and 1989 535 and 735 and the bolth let me down a few times. I will not DOWNgrade to a NEWER BMW ever again...