Misfiring CSL

[thompson]

Hi Guys
I think i have killed my csl. In the last few days i have been driving it very
hard since we had this good weather, why not.
Any way the car was running fine yesterday morning.Last night i was playing with my mates E92 M3 and all of a sudden i lost power on my car. So i had to pull over.
Engine management light was on and it was misfiring and running rough
so i switched it off straight away.I did not want to take a risk so i called the RAC who took their time to arrive.
The started the car and the misfire had disappeared and the engine light
was off, very weird!
They checked a few things and said its all okay and advised i get a further diagnosis check done by main dealer to be on the safe side.
which was fair enough.

Anyway i continued on my journey and i decided to give it more stick,
the same thing happened again but now i can control the misfire.
the engine misfires under load ONLY at 2000-3000rpm and then the misfire
clears away,if i drive it normally it is okay.

So now that pee'd me right of , this morning i took the car to my local
bmw dealer who said i need to book it in, anyway with a little bit of
hussling i got them to do a quick diagnoisis check which costed me
£117.00 but they could not find anything wrong with the car, they
stated the plugs and coils are okay and they need to do more tests,
i asked them to drive it underload so they did although they should of done this at the beginning but i was in no postion to argue with them,
However they want at least another 2-3 hours investigation time
but said it possibily might be the vanos system which could cost up to £2500.

At that point i fell of my chair in reception, my csl is fkd.
i have drove it back today and parked it up as i cant drive it anymore in this state.

Any ideas what it could be? Is this a common problem as the BMW
really were not that helpful, 117.00 down and no answers.

help please.....