My 1989 240sx sr13 can be going 60 mph and just shuts off, also going at any speed and it just shuts off. It will start back up each time. It does it often. I can drive 5 minutes and it just shuts down. All dash lights and electrical appears to be fine. Just tonight going 70mph and it just shuts down. Then stop to pay a toll, paid the cashier went 30 yards and shuts down, gong 20-30 mph just shuts down.. Checked all electrical, even changed out battery post clamps. Just continues. Any suggestions would be extremely helpful.