I have a 1998 540i e39, it sometimes seems as though the ignition sticks when I try to start it, when this happens it will idle roughly for a little while then cut out, generally if I leave it for a bit it may start OK, then after driving for awhile (tonight about 15kms) it will backfire a number of times, the problem comes and goes, I have taken it to the mechanic twice and so far he has replaced one of the coils and the ignition, but still the problem is there. I recently purchased and used a srs light reset tool and the problem only seems to have cropped up after that, can anyone offer any advice?