I have a 2005 MCS with a JCW intake and exhaust upgrade. I've owned the car for 2 years now and once a year the cars engine will just shutoff. Once was when I was getting off the freeway and it was heavily congested. A huge stop and go kind of a thing and all of a sudden the engine shutoff on me. After putting on park and turning the ignition again the car turned back on with no problems. I took it to the dealer and they insist that the car has no recollection of shutting down according to the key fob. They said it might be that the car felt something wrong and needed to restart, which is I believe is a load of crap.

Than just a few days ago in 110 California heat I was stuck in traffic on the freeway with the a/c on full speed and all of a sudden the a/c turned into a fan mode and trying to speed up since I lost alot of ground... the engine was shutoff again.

Has anyone had this problem before? It only seems to happen when it's serious stop and go traffic and the dealer insists there is nothing wrong with it. So far it has only happened twice but the most recent one was seriously a dangerous one. I hope someone has a solution to this or atleast have experienced this and might know something about it.