engine shut down

[dunitt]

Have a 99 Qx4 that twice in the last 2 years just died while driving. Each time had towed to a good shop that has a Nissan code scanner. the next morning it starts up and no codes. The last time you could smell fuel. Now it is running as great as it always does and my wife wants to sell it because she is scarred it will happen again. Has 160,000 miles on it, regular maintence, new plugs. Any thoughts.Thanks, Tom and Reggie