My volvo quit runing, actualy it stalled out wail driving. When I tryed to start it it backfired through the intake. When I started messing with it I edvenced the timeing and the car started but ren slopy and kept stallig. I have pulled the spark plugs after runing it for a few minutes and they were black ( overfulling black ). I have cheked all the ignition components and everithing cheked out fine. The full distributer makes a wired buzzing sound, I diconected one of the two wires that go to it ( full shut off as far as I know ) and the sound stoped ( the wires both have power + ). The car will run good for a few seconds once in a wail but the gos back to the same thing. Im confused, I have never dealt with this full sistem.