I have a 1991 4runner V6 with 160,000 miles. For years I have had an intermittent misfire. It only happens once in a while, and may not happen in an hour then twice in 15 minutes. Several folks have suggested it was the crank sensor (which it doesn't have), the vacuum advance (which it doesn't have), and spark plugs and/or wires (which have all been replaced twice. Three different mechanics have been unable to tell me what it was. It does not seem to be associated with engine or outside temperature, time I've been driving, speed, or RPM. Any ideas are very much welcomed.