728i E38 P reg.Help!

I bought a P reg BMW E38 728i Auto several months ago. It had been written off due to being put in in a ditch. There was no severe damage done other than the body work.
I've done all the bodywork repairs and getting to the mechanics of it, and that's where i am having problems. I've had it put on a computer and it came up with crank shaft sensor and thats all. Does anyone know if this would cause it to be running ok one minute and then just cut out? Its just done that today so i got out locked it, unlocked and it started up fine!
I've recently heard that this make and model was re called 5 times apparently so i don't know if that's true, but i'm worried that a bargain has now turned into a dud.
I did pull out a load of leaves and stuff that had got in near the rad so i guess that wouldn't help. It seems to be over heating but it doesn't look like the head.
Any help or ideas would be appreciated.

JohnnyBMW, as a fellow Brit, I would recommend that you also post your question at the 7 Series Register here: http://www.the7seriesregister.co.uk/forums/index.php?act=idx Registration is free and the guys and gals there I'm sure will get to the root of your problem and quickly too. Happy hunting!

Thanks for that, i have come across that site.

I should start with the crank sensor first, yes it will cause it to run rough & not necessarily all the time

I live in the colonies and my daily driver is a Neon. I had a crank position sensor go and the car would crank and run at first strt or when sitting for 30 minutes or more, however she would die when engine was hot. The problem was that the sensor was shorting out on a hot engine. I had the car towed to a technician who tried to code the car however it displayed no codes. The tech then started the car and let her idle until she died and then put the code scanner on and bingo crank position sensor. Get the sensor replaced and go from there.

A faulty crank sensor will cause that condition