Hi, I've bought a 1986 930 US spec. turbo not so long ago and have faced strange problem. Sometimes one of cylinders stops working. It happens and on cold and on hot engine, mostly on free revs, sometimes you can feel some kind of "jerks" in 1500-2000rpm. Spark plugs seems to be new. platinum NGK BPR7VX if I remember well.
I would like to make a list what could it be
